diff --git a/web/e2e/mobile.spec.ts b/web/e2e/mobile.spec.ts
index eaea48f..d7ebfee 100644
--- a/web/e2e/mobile.spec.ts
+++ b/web/e2e/mobile.spec.ts
@@ -1,7 +1,7 @@
 import { expect, test } from '@playwright/test';
 import { DOC, signIn } from './helpers';
 
-test('M1 — mobile : logo dans la barre, menu en tiroir, actions visibles, panneau en feuille', async ({ page }) => {
+test('M1 — mobile : logo dans la barre, menu en tiroir, actions visibles, panneau en feuille, réglages lisibles', async ({ page }) => {
   await signIn(page, 'Chiara');
   await page.goto('/');
   const brand = page.locator('header.topbar a.brand');
@@ -18,4 +18,10 @@ test('M1 — mobile : logo dans la barre, menu en tiroir, actions visibles, pann
   const first = page.locator('section.text article.unit').first();
   await first.getByRole('button', { name: 'Le vote' }).click();
   await expect(page.locator('aside.panel').getByText('Seuil : 50 voix pour')).toBeVisible();
+  // The settings of the formula read on a phone: the table of the five levels holds in the sheet.
+  await page.locator('aside.panel').getByRole('button', { name: 'Réglages de la formule' }).click();
+  await expect(page.locator('aside.panel').getByRole('tab', { name: 'Réglages' })).toBeInViewport();
+  await expect(page.locator('aside.panel table tbody tr')).toHaveCount(5);
+  const fits = await page.locator('aside.panel .scroll').evaluate((el) => el.scrollWidth <= el.clientWidth + 1);
+  expect(fits).toBe(true);
 });
diff --git a/web/e2e/reader.spec.ts b/web/e2e/reader.spec.ts
index 5c79cfc..c4ee3dc 100644
--- a/web/e2e/reader.spec.ts
+++ b/web/e2e/reader.spec.ts
@@ -60,6 +60,9 @@ test('C4 — les actions sont contextuelles, le vote s’ouvre en panneau', asyn
   await expect(panel.getByText('Il manque 50 voix pour.')).toBeVisible();
   await panel.getByText('La formule du seuil').click();
   await expect(panel.getByText(/W — électorat/)).toBeVisible();
+  // The level of the article sets M and G: the Raison d'être is at 3 / 5.
+  await expect(panel.getByText('M — majorité à pleine participation : 55 % — inertie 3 / 5 · moyenne')).toBeVisible();
+  await expect(panel.getByRole('button', { name: 'Réglages de la formule' })).toBeVisible();
   // The panel lives in the URL.
   await expect(page).toHaveURL(/onglet=vote/);
   await page.keyboard.press('Escape');
@@ -242,3 +245,57 @@ test('C19 — un article, une ligne : ses versions se déplient', async ({ page
   await expect(e3).toHaveAttribute('aria-expanded', 'false');
   await expect(versions).toHaveCount(0);
 });
+
+test('C20 — réglages de la formule et cinq crans', async ({ page }) => {
+  await signIn(page, 'Chiara');
+  await page.goto(DOC);
+  // From the head of the document: the scale of the group, at its usual turnout.
+  await page.getByRole('button', { name: 'Réglages de la formule' }).click();
+  await expect(page).toHaveURL(/onglet=reglages/);
+  const panel = page.locator('aside.panel');
+  await expect(panel.getByRole('heading', { name: 'Réglages de la formule' })).toBeVisible();
+  await expect(panel.getByText(/W — électorat : 5\s745/)).toBeVisible();
+  await expect(panel.getByText('C — minimum de voix pour : 50')).toBeVisible();
+  // No vote yet: the reference, twice C.
+  await expect(panel.getByText(/100 votants sur 5\s745 \(1,74 %\), deux fois C : la participation de référence/)).toBeVisible();
+  const rows = panel.locator('table tbody tr');
+  await expect(rows).toHaveCount(5);
+  await expect(rows.locator('th')).toHaveText([/1\s*très basse/, /2\s*basse/, /3\s*moyenne/, /4\s*haute/, /5\s*très haute/]);
+  await expect(rows.locator('td:nth-child(2)')).toHaveText(['50 %', '50 %', '55 %', '60 %', '66 %']);
+  await expect(rows.locator('td:nth-child(4)')).toHaveText(['60 %', '67 %', '75 %', '83 %', '90 %']);
+  // At 100 voters: C plus each level's share of the 50 votes beyond C.
+  const required = panel.locator('table tbody td.required');
+  await expect(required).toHaveText(['80', '84', '88', '92', '95']);
+  await expect(panel.getByText('celles exigées à la participation habituelle, 100 votants')).toBeVisible();
+  await page.keyboard.press('Escape');
+
+  // From the vote of an article: Unicité du compte is at 4 / 5, its row is marked.
+  const e1 = page.locator('section.text article.unit', { hasText: 'Unicité du compte' });
+  await e1.hover();
+  await e1.getByRole('button', { name: 'Le vote' }).click();
+  await expect(panel.getByRole('heading', { name: 'Inertie · 4 / 5 · haute' })).toBeVisible();
+  await panel.getByRole('button', { name: 'Réglages de la formule' }).click();
+  await expect(panel.locator('tr.current')).toHaveCount(1);
+  await expect(panel.locator('tr.current th')).toContainText('4');
+  await expect(panel.locator('tr.current th')).toContainText('cet article');
+  await expect(required).toHaveText(['50', '50', '50', '50', '50']);
+  await expect(panel.getByText('celles exigées à la participation de cette version, 0 votant.')).toBeVisible();
+  await page.keyboard.press('Escape');
+
+  // The five levels to choose from, in the test group; the change is voted at the article's level.
+  await page.goto(TEST_DOC);
+  const e2 = page.locator('section.text article.unit', { hasText: 'Réciprocité' });
+  await e2.hover();
+  await e2.getByRole('button', { name: 'Le vote' }).click();
+  await panel.getByText("Proposer un changement d'inertie").click();
+  const levels = panel.getByRole('radiogroup', { name: 'Nouvelle inertie' }).getByRole('radio');
+  await expect(levels).toHaveCount(5);
+  await expect(levels.nth(3)).toBeDisabled();
+  await expect(levels.nth(3)).toContainText('actuelle');
+  await expect(panel.getByText("Un changement d'inertie se vote lui-même à l'inertie de l'article : 4 / 5 · haute.")).toBeVisible();
+  await levels.nth(4).click();
+  await expect(levels.nth(4)).toHaveAttribute('aria-checked', 'true');
+  await panel.getByRole('button', { name: 'Soumettre au vote' }).click();
+  await expect(panel.getByRole('heading', { name: 'inertie vers 5 / 5 · très haute' })).toBeVisible();
+  await expect(panel.getByText('inertie 4 / 5 · haute', { exact: true })).toBeVisible();
+});
diff --git a/web/src/lib/components/DeepList.svelte b/web/src/lib/components/DeepList.svelte
index e09907a..ea00f7a 100644
--- a/web/src/lib/components/DeepList.svelte
+++ b/web/src/lib/components/DeepList.svelte
@@ -4,7 +4,7 @@
   // unfolds the others, each with its label, its water level and its marks — and
   // each opens its own vote.
   import { plain } from '$lib/markdown';
-  import { relationOf, titleOf } from '$lib/labels';
+  import { inertiaBadge, relationOf, titleOf } from '$lib/labels';
   import { i18n, t, type Key } from '$lib/i18n/index.svelte';
   import type { Proposal, Unit } from '$lib/types';
   import { excerpts, type Article } from '$lib/versions';
@@ -73,7 +73,7 @@
             <span class="meta">
               <span>{t('tally.short', { for: best.tally.for, against: best.tally.against })}</span>
               {#if relationOf(best, unit)}<span class="faint">{relationOf(best, unit)}</span>{/if}
-              {#if unit.inertia !== 'standard'}<span class="faint">{t(`inertia.${unit.inertia}`)}</span>{/if}
+              {#if unit.inertia !== 3}<span class="faint">{inertiaBadge(unit.inertia)}</span>{/if}
               {@render marks(best)}
             </span>
           </span>
@@ -94,7 +94,7 @@
               {#if a.leads}<span>{t('deep.lead', { label: labelOf(best, a) })}</span>{/if}
               <span>{t('tally.short', { for: best.tally.for, against: best.tally.against })}</span>
               {#if relationOf(best, unit)}<span class="faint">{relationOf(best, unit)}</span>{/if}
-              {#if unit.inertia !== 'standard'}<span class="faint">{t(`inertia.${unit.inertia}`)}</span>{/if}
+              {#if unit.inertia !== 3}<span class="faint">{inertiaBadge(unit.inertia)}</span>{/if}
               {#if best.evaluation?.wellRated}<span class="tag water">{t('deep.wellrated')}</span>{/if}
               {#if a.versions.some((p) => p.myVoteStale)}<span class="tag ochre">{t('deep.stale')}</span>{/if}
               {#if a.versions.some((p) => p.mine)}<span class="tag">{t('deep.mine')}</span>{/if}
diff --git a/web/src/lib/components/DocPanel.svelte b/web/src/lib/components/DocPanel.svelte
index 6d299fe..4141a61 100644
--- a/web/src/lib/components/DocPanel.svelte
+++ b/web/src/lib/components/DocPanel.svelte
@@ -3,6 +3,7 @@
   import { t } from '$lib/i18n/index.svelte';
   import { relationOf, titleOf } from '$lib/labels';
   import type { Lang } from '$lib/types';
+  import FormulaSettings from './FormulaSettings.svelte';
   import Icon from './Icon.svelte';
   import ProposeView from './ProposeView.svelte';
   import VoteView from './VoteView.svelte';
@@ -27,21 +28,30 @@
         ['vote', t('panel.vote'), !!voteId],
         ['proposals', `${t('panel.proposals')}${versions.length > 1 ? ` · ${versions.length}` : ''}`, !!unit],
         ['propose', t('panel.propose'), true],
+        // Reached from the head of the document or from a vote; shown while it is open.
+        ['settings', t('panel.settings'), panel.tab === 'settings'],
       ] as const
     ).filter(([, , show]) => show),
   );
   let body: HTMLElement | undefined = $state();
+  let tablist: HTMLElement | undefined = $state();
 
   $effect(() => {
     void panel.tab;
     void panel.proposalId;
     body?.scrollTo({ top: 0 });
   });
+
+  // On a narrow sheet the tabs scroll: the open one stays in sight.
+  $effect(() => {
+    void panel.tab;
+    tablist?.querySelector<HTMLElement>('[aria-selected="true"]')?.scrollIntoView({ block: 'nearest', inline: 'nearest' });
+  });
 </script>
 
 <aside class="panel card" aria-label={t('panel.vote')}>
   <div class="bar">
-    <div class="tabs" role="tablist">
+    <div class="tabs" role="tablist" bind:this={tablist}>
       {#each tabs as [key, label] (key)}
         <button role="tab" type="button" aria-selected={panel.tab === key} class:on={panel.tab === key} onclick={() => onchange({ ...panel, tab: key, prefill: null })}>{label}</button>
       {/each}
@@ -57,6 +67,7 @@
         {lang}
         onopen={(id) => onchange({ ...panel, proposalId: id, tab: 'vote' })}
         onpropose={(prefill) => onchange({ ...panel, tab: 'propose', prefill, draftId: null })}
+        onsettings={() => onchange({ ...panel, proposalId: voteId, tab: 'settings' })}
       />
     {:else if panel.tab === 'proposals' && unit}
       <ul class="versions">
@@ -82,6 +93,8 @@
         prefill={panel.prefill ?? null}
         ondone={(r) => onchange(r.proposalId ? { unitId: doc.proposal(r.proposalId)?.unitId ?? panel.unitId, proposalId: r.proposalId, tab: 'vote' } : { ...panel, tab: 'proposals' })}
       />
+    {:else if panel.tab === 'settings'}
+      <FormulaSettings {doc} proposalId={voteId} />
     {/if}
   </div>
 </aside>
diff --git a/web/src/lib/components/Formula.svelte b/web/src/lib/components/Formula.svelte
index b8d8b86..321d5b0 100644
--- a/web/src/lib/components/Formula.svelte
+++ b/web/src/lib/components/Formula.svelte
@@ -1,7 +1,8 @@
 <script lang="ts">
   // The threshold formula, typeset with native MathML — no KaTeX needed.
   import { i18n, t } from '$lib/i18n/index.svelte';
-  import type { Evaluation, Inertia, Tally } from '$lib/types';
+  import { inertiaBadge } from '$lib/labels';
+  import type { Evaluation, Inertia, LevelInfo, Tally } from '$lib/types';
 
   let {
     electorate,
@@ -9,21 +10,24 @@
     tally,
     evaluation,
     inertia,
-    presets,
+    levels,
     floor,
     base,
+    onsettings,
   }: {
     electorate: number;
     source: 'wot' | 'group';
     tally: Tally;
     evaluation: Evaluation | null;
     inertia: Inertia;
-    presets: { key: Inertia; majorityPct: number; gradient: number }[];
+    levels: LevelInfo[];
     floor: number;
     base: number;
+    /** Opens the settings of the formula (the five levels, the usual turnout). */
+    onsettings?: () => void;
   } = $props();
 
-  const p = $derived(presets.find((x) => x.key === inertia));
+  const p = $derived(levels.find((x) => x.level === inertia));
 </script>
 
 <details class="formula">
@@ -41,18 +45,23 @@
     <li>{t('formula.W', { n: i18n.number(electorate), source: t(source === 'wot' ? 'formula.W.wot' : 'formula.W.group') })}</li>
     <li>{t('formula.T', { n: tally.for + tally.against })}</li>
     {#if p}
-      <li>{t('formula.M', { n: p.majorityPct })} — {t(`inertia.${inertia}`)}</li>
-      <li>{t('formula.G', { n: p.gradient })}</li>
+      <li>{t('formula.M', { n: i18n.number(p.majorityPct) })} — {inertiaBadge(inertia)}</li>
+      <li>{t('formula.G', { n: i18n.number(Math.round(p.gradient * 1000) / 1000) })}</li>
     {/if}
-    <li>{t('formula.B', { n: base })}</li>
-    <li>{t('formula.C', { n: floor })}</li>
+    <li>{t('formula.B', { n: i18n.number(base) })}</li>
+    <li>{t('formula.C', { n: i18n.number(floor) })}</li>
     {#if evaluation}<li class="r">{t('formula.R', { n: evaluation.required })}</li>{/if}
   </ul>
   <p class="faint">{t('formula.reading')}</p>
 </details>
+{#if onsettings}
+  <button class="settings-link" type="button" onclick={onsettings}>{t('settings.title')}</button>
+{/if}
 
 <style>
   .formula {
+    /* A grid item may shrink below its widest line: the formula scrolls, the panel does not. */
+    min-width: 0;
     border-radius: var(--r-input);
     background: var(--surface-2);
     padding: 0.7rem 0.9rem;
@@ -86,4 +95,15 @@
   .faint {
     font-size: 0.85rem;
   }
+  .settings-link {
+    justify-self: start;
+    border: 0;
+    background: none;
+    padding: 0;
+    color: var(--water);
+    font-weight: 750;
+    font-size: 0.9rem;
+    text-decoration: underline;
+    text-underline-offset: 3px;
+  }
 </style>
diff --git a/web/src/lib/components/FormulaSettings.svelte b/web/src/lib/components/FormulaSettings.svelte
new file mode 100644
index 0000000..178c713
--- /dev/null
+++ b/web/src/lib/components/FormulaSettings.svelte
@@ -0,0 +1,195 @@
+<script lang="ts">
+  // The settings of the formula, read only: W and its source, C, B, the usual
+  // turnout of the group (median or reference) and the five levels on its
+  // scale. From the head of the document, the *for* votes asked are those of
+  // the usual turnout; from a version, those of its own turnout.
+  import { api } from '$lib/api';
+  import type { DocState } from '$lib/doc.svelte';
+  import { i18n, t } from '$lib/i18n/index.svelte';
+  import type { Inertia, LevelInfo } from '$lib/types';
+
+  let { doc, proposalId = null }: { doc: DocState; proposalId?: string | null } = $props();
+
+  interface Version {
+    levels: LevelInfo[];
+    proposal: { votedAtInertia: Inertia };
+  }
+
+  let version = $state<Version | null>(null);
+  $effect(() => {
+    const id = proposalId;
+    void doc.view;
+    version = null;
+    if (!id) return;
+    api
+      .get<Version>(`/proposals/${id}`)
+      .then((d) => {
+        if (proposalId === id) version = d;
+      })
+      .catch(() => {
+        version = null;
+      });
+  });
+
+  const view = $derived(doc.view);
+  const p = $derived(view?.doc.participation);
+  const levels = $derived(version?.levels ?? view?.levels ?? []);
+  const cast = $derived(levels[0]?.cast ?? 0);
+  const current = $derived(version?.proposal.votedAtInertia ?? null);
+  const pct = (ratio: number) => t('common.pct', { n: i18n.number(Math.round(ratio * 10000) / 100) });
+  const whole = (n: number) => t('common.pct', { n: i18n.number(n) });
+  const gradient = (g: number) => i18n.number(Math.round(g * 1000) / 1000);
+</script>
+
+{#if view && p}
+  <section class="settings" aria-labelledby="settings-title">
+    <h3 id="settings-title">{t('settings.title')}</h3>
+    <p class="muted">{t('settings.intro')}</p>
+
+    <ul class="values">
+      <li>{t('formula.W', { n: i18n.number(view.doc.electorate), source: t(view.doc.electorateSource === 'wot' ? 'formula.W.wot' : 'formula.W.group') })}</li>
+      <li>{t('formula.C', { n: i18n.number(view.doc.voteFloor) })}</li>
+      <li>{t('formula.B', { n: i18n.number(view.doc.formula.base) })}</li>
+    </ul>
+
+    <div class="usual">
+      <h4>{t('settings.usual')}</h4>
+      <p>
+        {#if p.source === 'median'}
+          {i18n.plural('settings.usual.median', p.voters, { electorate: i18n.number(view.doc.electorate), pct: pct(p.ratio), sample: p.sample })}
+        {:else}
+          {i18n.plural('settings.usual.reference', p.voters, { electorate: i18n.number(view.doc.electorate), pct: pct(p.ratio), min: p.minSample, sample: p.sample })}
+        {/if}
+      </p>
+      {#if p.bounded}<p class="faint small">{t('settings.usual.bounded', { lo: pct(p.bounds[0]), hi: pct(p.bounds[1]) })}</p>{/if}
+      <p class="faint small">{p.measuredAt ? t('settings.usual.when', { date: i18n.date(p.measuredAt) }) : t('settings.usual.never')}</p>
+    </div>
+
+    <h4>{t('settings.levels')}</h4>
+    <div class="scroll">
+      <table>
+        <thead>
+          <tr>
+            <th scope="col">{t('settings.col.level')}</th>
+            <th scope="col">M</th>
+            <th scope="col">G</th>
+            <th scope="col">{t('settings.col.share')}</th>
+            <th scope="col">{t('settings.col.required')}</th>
+          </tr>
+        </thead>
+        <tbody>
+          {#each levels as l (l.level)}
+            <tr class:current={l.level === current}>
+              <th scope="row">
+                <span class="lvl">
+                  <span class="k">{l.level}</span>
+                  <span class="name">{t(`inertia.name.${l.level}`)}</span>
+                  {#if l.level === current}<span class="tag water">{t('settings.current')}</span>{/if}
+                </span>
+              </th>
+              <td>{whole(l.majorityPct)}</td>
+              <td>{gradient(l.gradient)}</td>
+              <td>{whole(l.sharePct)}</td>
+              <td class="required">{l.required === null ? '—' : i18n.number(l.required)}</td>
+            </tr>
+          {/each}
+        </tbody>
+      </table>
+    </div>
+    <p class="faint small">{i18n.plural('settings.share.note', p.voters)}</p>
+    <p class="faint small">{i18n.plural(version ? 'settings.required.version' : 'settings.required.usual', cast)}</p>
+    <p class="faint small">{t('settings.reading')}</p>
+  </section>
+{/if}
+
+<style>
+  .settings {
+    display: grid;
+    gap: 0.8rem;
+    min-width: 0;
+  }
+  h3 {
+    font-family: var(--font-text);
+    font-weight: 500;
+    font-size: 1.35rem;
+  }
+  h4 {
+    margin: 0;
+    font-size: 0.92rem;
+    font-weight: 800;
+  }
+  .small {
+    font-size: 0.84rem;
+  }
+  .values {
+    margin: 0;
+    padding-left: 1.1rem;
+    font-size: 0.92rem;
+    display: grid;
+    gap: 0.15rem;
+  }
+  .usual {
+    display: grid;
+    gap: 0.3rem;
+    padding: 0.8rem 1rem;
+    border-radius: var(--r-card);
+    background: var(--water-wash);
+    font-size: 0.92rem;
+  }
+  .scroll {
+    overflow-x: auto;
+    border-radius: var(--r-input);
+    background: var(--surface-2);
+  }
+  table {
+    width: 100%;
+    border-collapse: collapse;
+    font-size: 0.88rem;
+    font-variant-numeric: tabular-nums;
+  }
+  th,
+  td {
+    padding: 0.45rem 0.55rem;
+    text-align: right;
+    white-space: nowrap;
+  }
+  thead th {
+    font-size: 0.74rem;
+    font-weight: 800;
+    letter-spacing: 0.04em;
+    color: var(--ink-soft);
+  }
+  th[scope='row'],
+  thead th:first-child {
+    text-align: left;
+  }
+  th[scope='row'] {
+    font-weight: 600;
+  }
+  .lvl {
+    display: inline-flex;
+    flex-wrap: wrap;
+    align-items: baseline;
+    gap: 0.35rem;
+  }
+  tbody tr:nth-child(odd) {
+    background: color-mix(in srgb, var(--surface) 55%, transparent);
+  }
+  tr.current {
+    background: var(--water-wash) !important;
+  }
+  .k {
+    font-weight: 800;
+    font-size: 1rem;
+  }
+  .name {
+    color: var(--ink-soft);
+    font-size: 0.8rem;
+  }
+  .required {
+    font-weight: 800;
+  }
+  .tag {
+    font-size: 0.68rem;
+  }
+</style>
diff --git a/web/src/lib/components/InertiaPicker.svelte b/web/src/lib/components/InertiaPicker.svelte
new file mode 100644
index 0000000..1ba35ce
--- /dev/null
+++ b/web/src/lib/components/InertiaPicker.svelte
@@ -0,0 +1,171 @@
+<script lang="ts">
+  // The inertia of an article: its level out of five, its past, the changes
+  // under vote, and the choice of a new level. A change of inertia is voted at
+  // the level of the article itself (ADR 0007).
+  import { api, ApiError } from '$lib/api';
+  import type { DocState } from '$lib/doc.svelte';
+  import { i18n, t, type Key } from '$lib/i18n/index.svelte';
+  import { inertiaLevel } from '$lib/labels';
+  import { INERTIA_LEVELS, type Inertia, type Unit } from '$lib/types';
+
+  let { doc, unit, onopen }: { doc: DocState; unit: Unit; onopen: (proposalId: string) => void } = $props();
+
+  let target = $state<Inertia | null>(null);
+  let busy = $state(false);
+  let error = $state('');
+  const open = $derived(unit.proposals.filter((x) => x.kind === 'inertia' && x.status === 'open'));
+  const level = (k: Inertia | null) => (k ? inertiaLevel(k) : '?');
+
+  async function submit() {
+    if (!target) return;
+    busy = true;
+    try {
+      const r = await api.post<{ id: string }>(`/units/${unit.id}/inertia`, { target });
+      target = null;
+      error = '';
+      await doc.reload();
+      onopen(r.id);
+    } catch (e) {
+      error = t(`error.${e instanceof ApiError ? e.code : 'internal'}` as Key);
+    } finally {
+      busy = false;
+    }
+  }
+</script>
+
+<section class="inertia" aria-labelledby="inertia-{unit.id}">
+  <h4 id="inertia-{unit.id}">{t('inertia.title')} · <span class="muted">{inertiaLevel(unit.inertia)}</span></h4>
+  <p class="faint small">{t('inertia.explain')}</p>
+  {#each unit.inertiaChanges as c (c.at + c.to)}
+    <p class="faint small">{t(`inertia.history.${c.cause}`, { from: level(c.from), to: level(c.to), date: i18n.date(c.at) })}</p>
+  {/each}
+  {#each open as ip (ip.id)}
+    <button class="link" type="button" onclick={() => onopen(ip.id)}>
+      {t('inertia.change.open', { level: level(ip.inertiaTarget) })} — {t('tally.short', { for: ip.tally.for, against: ip.tally.against })}
+    </button>
+  {/each}
+  <details>
+    <summary>{t('inertia.change')}</summary>
+    <div class="levels" role="radiogroup" aria-label={t('inertia.change.to')}>
+      {#each INERTIA_LEVELS as k (k)}
+        <button
+          type="button"
+          role="radio"
+          aria-checked={target === k}
+          class:on={target === k}
+          class:current={k === unit.inertia}
+          disabled={k === unit.inertia || busy}
+          onclick={() => (target = k)}
+        >
+          <span class="k">{k}</span>
+          <span class="name">{t(`inertia.name.${k}`)}</span>
+          {#if k === unit.inertia}<span class="cur">{t('inertia.change.current')}</span>{/if}
+        </button>
+      {/each}
+    </div>
+    <button class="btn small" type="button" disabled={!target || busy} onclick={submit}>{t('inertia.change.submit')}</button>
+    <p class="faint small">{t('inertia.change.note', { level: inertiaLevel(unit.inertia) })}</p>
+  </details>
+  {#if error}<p class="warn" role="alert">{error}</p>{/if}
+</section>
+
+<style>
+  .inertia {
+    display: grid;
+    gap: 0.5rem;
+    min-width: 0;
+  }
+  h4 {
+    margin: 0;
+    font-size: 0.92rem;
+    font-weight: 800;
+  }
+  .small {
+    font-size: 0.84rem;
+  }
+  details {
+    display: grid;
+    gap: 0.6rem;
+  }
+  details > summary {
+    cursor: pointer;
+    font-weight: 750;
+    color: var(--water);
+    font-size: 0.92rem;
+  }
+  details[open] > summary {
+    margin-bottom: 0.6rem;
+  }
+  details > :not(summary) + :not(summary) {
+    margin-top: 0.6rem;
+  }
+  .levels {
+    display: grid;
+    grid-template-columns: repeat(5, minmax(0, 1fr));
+    gap: 0.35rem;
+  }
+  .levels button {
+    display: grid;
+    justify-items: center;
+    align-content: start;
+    gap: 0.1rem;
+    min-height: 4rem;
+    padding: 0.5rem 0.25rem;
+    border: 0;
+    border-radius: var(--r-input);
+    background: var(--surface-2);
+    color: var(--ink-soft);
+    text-align: center;
+    transition: background-color 0.15s var(--ease), color 0.15s var(--ease);
+  }
+  .levels button:hover:not(:disabled) {
+    background: var(--water-wash);
+    color: var(--ink);
+  }
+  .levels button.current {
+    background: transparent;
+    cursor: default;
+  }
+  .levels button.on,
+  .levels button.on:hover {
+    background: var(--water);
+    color: var(--on-water);
+  }
+  .k {
+    font-size: 1.15rem;
+    font-weight: 800;
+    font-variant-numeric: tabular-nums;
+  }
+  .name {
+    font-size: 0.74rem;
+    font-weight: 700;
+    line-height: 1.15;
+  }
+  .cur {
+    font-size: 0.68rem;
+    font-weight: 800;
+    color: var(--water);
+  }
+  .btn {
+    justify-self: start;
+  }
+  .link {
+    border: 0;
+    background: none;
+    padding: 0;
+    color: var(--water);
+    font-weight: 700;
+    text-align: left;
+    font-size: 0.9rem;
+  }
+  .warn {
+    color: var(--ochre);
+    font-weight: 700;
+    font-size: 0.9rem;
+  }
+  @media (prefers-reduced-motion: reduce) {
+    .levels button {
+      transition: none;
+    }
+  }
+</style>
diff --git a/web/src/lib/components/VoteView.svelte b/web/src/lib/components/VoteView.svelte
index 2ea98c6..a3495f8 100644
--- a/web/src/lib/components/VoteView.svelte
+++ b/web/src/lib/components/VoteView.svelte
@@ -2,11 +2,12 @@
   import { api, ApiError } from '$lib/api';
   import { shown, type DocState } from '$lib/doc.svelte';
   import { i18n, t, type Key } from '$lib/i18n/index.svelte';
-  import { titleOf } from '$lib/labels';
+  import { inertiaBadge, titleOf } from '$lib/labels';
   import { toasts } from '$lib/toast.svelte';
-  import type { DiffPart, Entered, Inertia, Lang, Proposal } from '$lib/types';
+  import type { DiffPart, Entered, Inertia, Lang, LevelInfo, Proposal } from '$lib/types';
   import DiffText from './DiffText.svelte';
   import Formula from './Formula.svelte';
+  import InertiaPicker from './InertiaPicker.svelte';
   import Prose from './Prose.svelte';
   import WaterLevel from './WaterLevel.svelte';
 
@@ -16,12 +17,14 @@
     lang,
     onopen,
     onpropose,
+    onsettings,
   }: {
     doc: DocState;
     proposalId: string;
     lang: Lang;
     onopen: (proposalId: string) => void;
     onpropose: (prefill: { title: string; body: string }) => void;
+    onsettings?: () => void;
   } = $props();
 
   interface Detail {
@@ -36,13 +39,13 @@
     }[];
     electorate: number;
     voteFloor: number;
+    levels: LevelInfo[];
   }
 
   let detail = $state<Detail | null>(null);
   let busy = $state(false);
   let showDiff = $state(false);
   let error = $state('');
-  let inertiaTarget = $state<Inertia | ''>('');
   let typoOpen = $state(false);
   let typoTitle = $state('');
   let typoBody = $state('');
@@ -58,7 +61,6 @@
   const source = $derived(view?.doc.sourceLang ?? 'fr');
   const text = $derived(p ? shown(p, lang, source) : null);
   const votable = $derived(p?.status === 'open' || p?.status === 'in_force');
-  const inertiaOpen = $derived((unit?.proposals ?? []).filter((x) => x.kind === 'inertia' && x.status === 'open'));
   const signalTargets = $derived(
     (view?.units ?? []).flatMap((u) =>
       [u.inForce, ...u.proposals]
@@ -122,21 +124,6 @@
     }
   }
 
-  async function proposeInertia() {
-    if (!unit || !inertiaTarget) return;
-    busy = true;
-    try {
-      const r = await api.post<{ id: string }>(`/units/${unit.id}/inertia`, { target: inertiaTarget });
-      inertiaTarget = '';
-      await doc.reload();
-      onopen(r.id);
-    } catch (e) {
-      error = message(e);
-    } finally {
-      busy = false;
-    }
-  }
-
   async function saveTypo(e: SubmitEvent) {
     e.preventDefault();
     busy = true;
@@ -250,7 +237,7 @@
             <p class="muted">{t('tally.required', { n: p.evaluation.required })}</p>
             <p class="state">{p.evaluation.reached ? t('tally.reached') : i18n.plural('tally.missing', p.evaluation.missing)}</p>
           {/if}
-          <p class="faint small">{t(`inertia.${p.votedAtInertia}`)}</p>
+          <p class="faint small">{inertiaBadge(p.votedAtInertia)}</p>
         </div>
       </div>
       {#if p.blocked}<p class="warn">{t('vote.blocked')}</p>{/if}
@@ -271,30 +258,9 @@
       {/if}
     </section>
 
-    {#if p.kind !== 'inertia' && unit}
-      <section class="sub">
-        <h4>{t('inertia.title')} · <span class="muted">{t(`inertia.level.${unit.inertia}`)}</span></h4>
-        <p class="faint small">{t('inertia.explain')}</p>
-        {#each inertiaOpen as ip (ip.id)}
-          <button class="link" type="button" onclick={() => onopen(ip.id)}>{t('inertia.change.open', { level: t(`inertia.level.${ip.inertiaTarget ?? 'standard'}`) })} — {t('tally.short', { for: ip.tally.for, against: ip.tally.against })}</button>
-        {/each}
-        <details>
-          <summary>{t('inertia.change')}</summary>
-          <div class="row">
-            <select class="select" bind:value={inertiaTarget} aria-label={t('inertia.change.to')}>
-              <option value="" disabled>{t('inertia.change.to')}</option>
-              {#each ['low', 'standard', 'high', 'max'] as const as level (level)}
-                {#if level !== unit.inertia}<option value={level}>{t(`inertia.level.${level}`)}</option>{/if}
-              {/each}
-            </select>
-            <button class="btn small" type="button" disabled={!inertiaTarget || busy} onclick={proposeInertia}>{t('inertia.change.submit')}</button>
-          </div>
-          <p class="faint small">{t('inertia.change.note', { level: t(`inertia.level.${({ low: 'standard', standard: 'high', high: 'max', max: 'max' } as const)[unit.inertia]}`) })}</p>
-        </details>
-      </section>
-    {/if}
+    {#if p.kind !== 'inertia' && unit}<InertiaPicker {doc} {unit} {onopen} />{/if}
 
-    <Formula electorate={detail.electorate} source={view.doc.electorateSource} tally={p.tally} evaluation={p.evaluation} inertia={p.votedAtInertia} presets={view.inertia} floor={detail.voteFloor} base={view.doc.formula.base} />
+    <Formula electorate={detail.electorate} source={view.doc.electorateSource} tally={p.tally} evaluation={p.evaluation} inertia={p.votedAtInertia} levels={detail.levels} floor={detail.voteFloor} base={view.doc.formula.base} {onsettings} />
 
     {#if p.kind === 'text' && (p.status === 'in_force' || p.origin === 'seed' || p.mine) && votable}
       <section class="sub">
@@ -474,11 +440,6 @@
     color: var(--water);
     font-size: 0.92rem;
   }
-  .row {
-    display: flex;
-    gap: 0.5rem;
-    margin-top: 0.5rem;
-  }
   .form {
     display: grid;
     gap: 0.6rem;
@@ -490,15 +451,6 @@
   .textarea.short {
     min-height: 5rem;
   }
-  .link {
-    border: 0;
-    background: none;
-    padding: 0;
-    color: var(--water);
-    font-weight: 700;
-    text-align: left;
-    font-size: 0.9rem;
-  }
   .history {
     margin: 0;
     padding-left: 1rem;
diff --git a/web/src/lib/doc.svelte.ts b/web/src/lib/doc.svelte.ts
index c85aefe..99a42f8 100644
--- a/web/src/lib/doc.svelte.ts
+++ b/web/src/lib/doc.svelte.ts
@@ -7,7 +7,7 @@ import type { GroupView } from './group';
 import type { DocView, Lang, PreviewUnit, Proposal, Translation, Unit } from './types';
 
 export type View = 'inforce' | 'wellrated' | 'all';
-export type Tab = 'vote' | 'proposals' | 'propose';
+export type Tab = 'vote' | 'proposals' | 'propose' | 'settings';
 
 export interface PanelState {
   unitId: string | null;
diff --git a/web/src/lib/i18n/en.ts b/web/src/lib/i18n/en.ts
index 4848656..c4a8e1f 100644
--- a/web/src/lib/i18n/en.ts
+++ b/web/src/lib/i18n/en.ts
@@ -134,7 +134,7 @@ export const en: Messages = {
   'deep.rival': 'would replace “{title}”',
   'deep.addition': 'new article',
   'deep.removal': 'removal of “{title}”',
-  'deep.inertia': 'inertia: {level}',
+  'deep.inertia': 'inertia to {level}',
   'deep.blocked': 'blocked',
   'deep.mine': 'your proposal',
   'deep.stale': 'needs reconfirming',
@@ -163,19 +163,19 @@ export const en: Messages = {
   'tally.missing.other': '{n} more votes in favor needed.',
   'tally.reached': 'Threshold reached.',
   'tally.level': 'Level: {pct}% of the threshold',
+  'inertia.name.1': 'very low',
+  'inertia.name.2': 'low',
+  'inertia.name.3': 'medium',
+  'inertia.name.4': 'high',
+  'inertia.name.5': 'very high',
+  'inertia.level': '{k} / 5 · {name}',
+  'inertia.badge': 'inertia {level}',
 
-  'inertia.low': 'low inertia',
-  'inertia.standard': 'standard inertia',
-  'inertia.high': 'high inertia',
-  'inertia.max': 'maximum inertia',
-  'inertia.level.low': 'low',
-  'inertia.level.standard': 'standard',
-  'inertia.level.high': 'high',
-  'inertia.level.max': 'maximum',
 
   'panel.vote': 'Voting',
   'panel.proposals': 'Proposals',
   'panel.propose': 'Propose',
+  'panel.settings': 'Settings',
   'panel.close': 'Close panel',
   'panel.inforce': 'In force',
   'panel.proposal': 'Proposal',
@@ -205,9 +205,12 @@ export const en: Messages = {
   'inertia.explain': 'The higher the inertia, the more votes it takes to change this text when few people vote.',
   'inertia.change': 'Propose an inertia change',
   'inertia.change.to': 'New inertia',
-  'inertia.change.note': 'An inertia change is itself voted on with the next inertia up: {level}.',
+  'inertia.change.note': "A change of inertia is itself voted at the article's inertia: {level}.",
   'inertia.change.submit': 'Submit to vote',
   'inertia.change.open': 'Inertia change in progress: to {level}',
+  'inertia.change.current': 'current',
+  'inertia.history.vote': 'Went from {from} to {to} on {date}, by a vote.',
+  'inertia.history.amendment': 'Went from {from} to {to} on {date}: starting setting of the text.',
 
   'formula.title': 'The threshold formula',
   'formula.intro': 'The number of votes in favor required, R, depends on turnout:',
@@ -221,6 +224,29 @@ export const en: Messages = {
   'formula.C': 'C — minimum votes in favor: {n}',
   'formula.R': 'R — current threshold: {n} votes in favor',
   'formula.reading': 'At low turnout, near-unanimity is needed; when everyone votes, majority M is enough. Nothing passes with fewer than C votes in favor.',
+  'common.pct': '{n}%',
+  'settings.title': 'Formula settings',
+  'settings.intro': 'To change a text, the group asks for a number of votes in favour that depends on its electorate, its usual turnout and the inertia of the article.',
+  'settings.usual': 'Usual turnout',
+  'settings.usual.median.one': '{n} voter out of {electorate} ({pct}): the median of the {sample} proposals voted on over the past year.',
+  'settings.usual.median.other': '{n} voters out of {electorate} ({pct}): the median of the {sample} proposals voted on over the past year.',
+  'settings.usual.reference.one': '{n} voter out of {electorate} ({pct}), twice C: the reference turnout, until the group has voted on {min} proposals ({sample} so far).',
+  'settings.usual.reference.other': '{n} voters out of {electorate} ({pct}), twice C: the reference turnout, until the group has voted on {min} proposals ({sample} so far).',
+  'settings.usual.bounded': 'Kept between {lo} and {hi} of the electorate.',
+  'settings.usual.when': 'Measured once a day, last on {date}.',
+  'settings.usual.never': 'Measured once a day.',
+  'settings.levels': 'The five levels',
+  'settings.col.level': 'Level',
+  'settings.col.share': 'Share asked',
+  'settings.col.required': 'Votes for',
+  'settings.current': 'this article',
+  'settings.share.note.one': 'Share asked: the share of votes in favour beyond C when {n} person votes, as usual.',
+  'settings.share.note.other': 'Share asked: the share of votes in favour beyond C when {n} people vote, as usual.',
+  'settings.required.version.one': 'Votes for: those asked at the turnout of this version, {n} voter.',
+  'settings.required.version.other': 'Votes for: those asked at the turnout of this version, {n} voters.',
+  'settings.required.usual.one': 'Votes for: those asked at the usual turnout, {n} voter.',
+  'settings.required.usual.other': 'Votes for: those asked at the usual turnout, {n} voters.',
+  'settings.reading': 'At each level, the group asks for its share of votes in favour beyond C when it votes as usual; the more voters, the closer it comes to M. Nothing passes below C votes in favour.',
 
   'history.title': 'Corrections',
   'history.initial': 'initial text',
diff --git a/web/src/lib/i18n/es.ts b/web/src/lib/i18n/es.ts
index 4bb20ef..717aeeb 100644
--- a/web/src/lib/i18n/es.ts
+++ b/web/src/lib/i18n/es.ts
@@ -134,7 +134,7 @@ export const es: Messages = {
   'deep.rival': 'reemplazaría «{title}»',
   'deep.addition': 'artículo nuevo',
   'deep.removal': 'retirada de «{title}»',
-  'deep.inertia': 'inercia: {level}',
+  'deep.inertia': 'inercia a {level}',
   'deep.blocked': 'bloqueada',
   'deep.mine': 'tu propuesta',
   'deep.stale': 'por reconfirmar',
@@ -163,19 +163,19 @@ export const es: Messages = {
   'tally.missing.other': 'Faltan {n} votos a favor.',
   'tally.reached': 'Umbral alcanzado.',
   'tally.level': 'Nivel: {pct} % del umbral',
+  'inertia.name.1': 'muy baja',
+  'inertia.name.2': 'baja',
+  'inertia.name.3': 'media',
+  'inertia.name.4': 'alta',
+  'inertia.name.5': 'muy alta',
+  'inertia.level': '{k} / 5 · {name}',
+  'inertia.badge': 'inercia {level}',
 
-  'inertia.low': 'inercia baja',
-  'inertia.standard': 'inercia estándar',
-  'inertia.high': 'inercia alta',
-  'inertia.max': 'inercia máxima',
-  'inertia.level.low': 'baja',
-  'inertia.level.standard': 'estándar',
-  'inertia.level.high': 'alta',
-  'inertia.level.max': 'máxima',
 
   'panel.vote': 'Votación',
   'panel.proposals': 'Propuestas',
   'panel.propose': 'Proponer',
+  'panel.settings': 'Ajustes',
   'panel.close': 'Cerrar el panel',
   'panel.inforce': 'En vigor',
   'panel.proposal': 'Propuesta',
@@ -205,9 +205,12 @@ export const es: Messages = {
   'inertia.explain': 'Cuanto más alta es la inercia, más votos hacen falta para cambiar este texto cuando vota poca gente.',
   'inertia.change': 'Proponer un cambio de inercia',
   'inertia.change.to': 'Nueva inercia',
-  'inertia.change.note': 'Un cambio de inercia se vota a su vez con la inercia superior: {level}.',
+  'inertia.change.note': 'Un cambio de inercia se vota a su vez con la inercia del artículo: {level}.',
   'inertia.change.submit': 'Someter a votación',
   'inertia.change.open': 'Cambio de inercia en curso: a {level}',
+  'inertia.change.current': 'actual',
+  'inertia.history.vote': 'Pasó de {from} a {to} el {date}, por votación.',
+  'inertia.history.amendment': 'Pasó de {from} a {to} el {date}: ajuste inicial del texto.',
 
   'formula.title': 'La fórmula del umbral',
   'formula.intro': 'El número de votos a favor exigido, R, depende de la participación:',
@@ -221,6 +224,29 @@ export const es: Messages = {
   'formula.C': 'C — mínimo de votos a favor: {n}',
   'formula.R': 'R — umbral actual: {n} votos a favor',
   'formula.reading': 'Con poca participación, hace falta casi la unanimidad; cuando vota todo el mundo, basta la mayoría M. Nada pasa con menos de C votos a favor.',
+  'common.pct': '{n} %',
+  'settings.title': 'Ajustes de la fórmula',
+  'settings.intro': 'Para cambiar un texto, el grupo pide un número de votos a favor que depende de su electorado, de su participación habitual y de la inercia del artículo.',
+  'settings.usual': 'Participación habitual',
+  'settings.usual.median.one': '{n} votante de {electorate} ({pct}): la mediana de las {sample} propuestas votadas en el último año.',
+  'settings.usual.median.other': '{n} votantes de {electorate} ({pct}): la mediana de las {sample} propuestas votadas en el último año.',
+  'settings.usual.reference.one': '{n} votante de {electorate} ({pct}), dos veces C: la participación de referencia, hasta que el grupo haya votado {min} propuestas ({sample} por ahora).',
+  'settings.usual.reference.other': '{n} votantes de {electorate} ({pct}), dos veces C: la participación de referencia, hasta que el grupo haya votado {min} propuestas ({sample} por ahora).',
+  'settings.usual.bounded': 'Mantenida entre el {lo} y el {hi} del electorado.',
+  'settings.usual.when': 'Medida una vez al día, la última el {date}.',
+  'settings.usual.never': 'Medida una vez al día.',
+  'settings.levels': 'Los cinco niveles',
+  'settings.col.level': 'Nivel',
+  'settings.col.share': 'Proporción exigida',
+  'settings.col.required': 'Votos a favor',
+  'settings.current': 'este artículo',
+  'settings.share.note.one': 'Proporción exigida: la parte de votos a favor más allá de C cuando vota {n} persona, como de costumbre.',
+  'settings.share.note.other': 'Proporción exigida: la parte de votos a favor más allá de C cuando votan {n} personas, como de costumbre.',
+  'settings.required.version.one': 'Votos a favor: los exigidos con la participación de esta versión, {n} votante.',
+  'settings.required.version.other': 'Votos a favor: los exigidos con la participación de esta versión, {n} votantes.',
+  'settings.required.usual.one': 'Votos a favor: los exigidos con la participación habitual, {n} votante.',
+  'settings.required.usual.other': 'Votos a favor: los exigidos con la participación habitual, {n} votantes.',
+  'settings.reading': 'En cada nivel, el grupo pide su parte de votos a favor más allá de C cuando vota como de costumbre; cuantos más votantes, más se acerca a M. Nada pasa con menos de C votos a favor.',
 
   'history.title': 'Correcciones',
   'history.initial': 'texto inicial',
diff --git a/web/src/lib/i18n/fr.ts b/web/src/lib/i18n/fr.ts
index e511159..f8d87d3 100644
--- a/web/src/lib/i18n/fr.ts
+++ b/web/src/lib/i18n/fr.ts
@@ -137,7 +137,7 @@ export const fr = {
   'deep.rival': 'remplacerait « {title} »',
   'deep.addition': 'nouvel article',
   'deep.removal': 'retrait de « {title} »',
-  'deep.inertia': 'inertie : {level}',
+  'deep.inertia': 'inertie vers {level}',
   'deep.blocked': 'bloquée',
   'deep.mine': 'ta proposition',
   'deep.stale': 'à reconfirmer',
@@ -166,19 +166,19 @@ export const fr = {
   'tally.missing.other': 'Il manque {n} voix pour.',
   'tally.reached': 'Seuil atteint.',
   'tally.level': 'Niveau : {pct} % du seuil',
+  'inertia.name.1': 'très basse',
+  'inertia.name.2': 'basse',
+  'inertia.name.3': 'moyenne',
+  'inertia.name.4': 'haute',
+  'inertia.name.5': 'très haute',
+  'inertia.level': '{k} / 5 · {name}',
+  'inertia.badge': 'inertie {level}',
 
-  'inertia.low': 'inertie faible',
-  'inertia.standard': 'inertie standard',
-  'inertia.high': 'inertie haute',
-  'inertia.max': 'inertie maximale',
-  'inertia.level.low': 'faible',
-  'inertia.level.standard': 'standard',
-  'inertia.level.high': 'haute',
-  'inertia.level.max': 'maximale',
 
   'panel.vote': 'Le vote',
   'panel.proposals': 'Propositions',
   'panel.propose': 'Proposer',
+  'panel.settings': 'Réglages',
   'panel.close': 'Fermer le panneau',
   'panel.inforce': 'En vigueur',
   'panel.proposal': 'Proposition',
@@ -208,9 +208,12 @@ export const fr = {
   'inertia.explain': "Plus l'inertie est haute, plus il faut de voix pour changer ce texte quand peu de gens votent.",
   'inertia.change': "Proposer un changement d'inertie",
   'inertia.change.to': 'Nouvelle inertie',
-  'inertia.change.note': "Un changement d'inertie se vote lui-même avec l'inertie au-dessus : {level}.",
+  'inertia.change.note': "Un changement d'inertie se vote lui-même à l'inertie de l'article : {level}.",
   'inertia.change.submit': 'Soumettre au vote',
   'inertia.change.open': "Changement d'inertie en cours : vers {level}",
+  'inertia.change.current': 'actuelle',
+  'inertia.history.vote': 'Passée de {from} à {to} le {date}, par un vote.',
+  'inertia.history.amendment': 'Passée de {from} à {to} le {date} : réglage de départ du texte.',
 
   'formula.title': 'La formule du seuil',
   'formula.intro': 'Le nombre de voix pour exigé, R, dépend de la participation :',
@@ -224,6 +227,29 @@ export const fr = {
   'formula.C': 'C — minimum de voix pour : {n}',
   'formula.R': 'R — seuil actuel : {n} voix pour',
   'formula.reading': "À faible participation, il faut presque l'unanimité ; quand tout le monde vote, la majorité M suffit. Rien ne passe sous C voix pour.",
+  'common.pct': '{n} %',
+  'settings.title': 'Réglages de la formule',
+  'settings.intro': "Pour changer un texte, le groupe demande un nombre de voix pour qui dépend de son électorat, de sa participation habituelle et de l'inertie de l'article.",
+  'settings.usual': 'Participation habituelle',
+  'settings.usual.median.one': '{n} votant sur {electorate} ({pct}) : la médiane des {sample} propositions votées depuis un an.',
+  'settings.usual.median.other': '{n} votants sur {electorate} ({pct}) : la médiane des {sample} propositions votées depuis un an.',
+  'settings.usual.reference.one': "{n} votant sur {electorate} ({pct}), deux fois C : la participation de référence, tant que le groupe n'a pas voté sur {min} propositions ({sample} pour l'instant).",
+  'settings.usual.reference.other': "{n} votants sur {electorate} ({pct}), deux fois C : la participation de référence, tant que le groupe n'a pas voté sur {min} propositions ({sample} pour l'instant).",
+  'settings.usual.bounded': "Ramenée entre {lo} et {hi} de l'électorat.",
+  'settings.usual.when': 'Mesurée une fois par jour, la dernière fois le {date}.',
+  'settings.usual.never': 'Mesurée une fois par jour.',
+  'settings.levels': 'Les cinq crans',
+  'settings.col.level': 'Cran',
+  'settings.col.share': 'Part exigée',
+  'settings.col.required': 'Voix pour',
+  'settings.current': 'cet article',
+  'settings.share.note.one': "Part exigée : la part de « pour » au-delà de C quand {n} personne vote, comme d'habitude.",
+  'settings.share.note.other': "Part exigée : la part de « pour » au-delà de C quand {n} personnes votent, comme d'habitude.",
+  'settings.required.version.one': 'Voix pour : celles exigées à la participation de cette version, {n} votant.',
+  'settings.required.version.other': 'Voix pour : celles exigées à la participation de cette version, {n} votants.',
+  'settings.required.usual.one': 'Voix pour : celles exigées à la participation habituelle, {n} votant.',
+  'settings.required.usual.other': 'Voix pour : celles exigées à la participation habituelle, {n} votants.',
+  'settings.reading': "À chaque cran, le groupe demande sa part de « pour » au-delà de C quand il vote comme d'habitude ; plus il y a de votants, plus elle se rapproche de M. Rien ne passe sous C voix pour.",
 
   'history.title': 'Corrections',
   'history.initial': 'texte initial',
diff --git a/web/src/lib/labels.ts b/web/src/lib/labels.ts
index f510a5d..25612f0 100644
--- a/web/src/lib/labels.ts
+++ b/web/src/lib/labels.ts
@@ -1,10 +1,20 @@
 import { t } from './i18n/index.svelte';
-import type { Proposal, Unit } from './types';
+import type { Inertia, Proposal, Unit } from './types';
+
+/** « 3 / 5 · moyenne ». */
+export function inertiaLevel(k: Inertia): string {
+  return t('inertia.level', { k, name: t(`inertia.name.${k}`) });
+}
+
+/** « inertie 3 / 5 · moyenne ». */
+export function inertiaBadge(k: Inertia): string {
+  return t('inertia.badge', { level: inertiaLevel(k) });
+}
 
 /** What a proposal is, in words, whatever its kind. */
 export function titleOf(p: Proposal, unit: Unit | undefined): string {
   if (p.kind === 'inertia' && p.inertiaTarget) {
-    return t('deep.inertia', { level: t(`inertia.level.${p.inertiaTarget}`) });
+    return t('deep.inertia', { level: inertiaLevel(p.inertiaTarget) });
   }
   if (p.kind === 'remove') return t('deep.removal', { title: unit?.inForce?.title ?? p.title });
   return p.title;
diff --git a/web/src/lib/types.ts b/web/src/lib/types.ts
index 952fdfd..123faa0 100644
--- a/web/src/lib/types.ts
+++ b/web/src/lib/types.ts
@@ -1,6 +1,40 @@
 export type Lang = 'fr' | 'en' | 'es';
 export type LangMap = Partial<Record<Lang, string>>;
-export type Inertia = 'low' | 'standard' | 'high' | 'max';
+/** The five levels of inertia, 1 (lightest) to 5 (heaviest); 3 by default. */
+export type Inertia = 1 | 2 | 3 | 4 | 5;
+export const INERTIA_LEVELS: Inertia[] = [1, 2, 3, 4, 5];
+
+/** One level on the group's scale: M and G of the formula, s_k, and the *for* votes asked at `cast` votes. */
+export interface LevelInfo {
+  level: Inertia;
+  majorityPct: number;
+  gradient: number;
+  sharePct: number;
+  cast: number;
+  required: number | null;
+}
+
+/** p̃ — the usual turnout of the group, measured once a day (or the reference 2C/W). */
+export interface ParticipationInfo {
+  ratio: number;
+  source: 'median' | 'reference';
+  sample: number;
+  median: number | null;
+  bounded: boolean;
+  voters: number;
+  minSample: number;
+  windowDays: number;
+  everyHours: number;
+  bounds: [number, number];
+  measuredAt: string | null;
+}
+
+export interface InertiaChange {
+  from: Inertia | null;
+  to: Inertia | null;
+  cause: 'vote' | 'amendment';
+  at: string;
+}
 
 export interface Me {
   id: string;
@@ -75,6 +109,7 @@ export interface Unit {
   section: string | null;
   position: number;
   inertia: Inertia;
+  inertiaChanges: InertiaChange[];
   inForce: Proposal | null;
   proposals: Proposal[];
 }
@@ -103,10 +138,12 @@ export interface DocView {
     electorate: number;
     electorateSource: 'wot' | 'group';
     formula: { base: number };
+    participation: ParticipationInfo;
     publication: Publication;
   };
   units: Unit[];
-  inertia: { key: Inertia; majorityPct: number; gradient: number }[];
+  /** The five levels, with the *for* votes asked at the usual turnout. */
+  levels: LevelInfo[];
 }
 
 export type DiffPart = { op: 'same' | 'added' | 'removed'; text: string };
diff --git a/web/src/routes/g/[group]/docs/[doc]/+page.svelte b/web/src/routes/g/[group]/docs/[doc]/+page.svelte
index 2aaab58..9ad0282 100644
--- a/web/src/routes/g/[group]/docs/[doc]/+page.svelte
+++ b/web/src/routes/g/[group]/docs/[doc]/+page.svelte
@@ -20,8 +20,8 @@
   });
 
   // The panel lives in the URL: a link (or a feedback report) reopens it.
-  const TABS: Record<string, Tab> = { vote: 'vote', propositions: 'proposals', proposer: 'propose' };
-  const TAB_NAMES: Record<Tab, string> = { vote: 'vote', proposals: 'propositions', propose: 'proposer' };
+  const TABS: Record<string, Tab> = { vote: 'vote', propositions: 'proposals', proposer: 'propose', reglages: 'settings' };
+  const TAB_NAMES: Record<Tab, string> = { vote: 'vote', proposals: 'propositions', propose: 'proposer', settings: 'reglages' };
   let prefill = $state<PanelState['prefill']>(null);
   const panel = $derived.by((): PanelState | null => {
     const q = page.url.searchParams;
@@ -77,6 +77,7 @@
       <p class="facts faint">
         {i18n.plural('docs.inForce', doc.inForce.length)} · {i18n.plural('docs.open', doc.open.length)}
         {#if view.doc.publication.state === 'done'} · {t('doc.published')}{:else if view.doc.publication.state === 'pending'} · {t('doc.publish.pending')}{/if}
+        · <button class="linkish" type="button" onclick={() => openPanel({ unitId: null, proposalId: null, tab: 'settings' })}>{t('settings.title')}</button>
       </p>
 
       <div class="controls">
diff --git a/web/tests/unit/inertia.test.ts b/web/tests/unit/inertia.test.ts
new file mode 100644
index 0000000..39fed47
--- /dev/null
+++ b/web/tests/unit/inertia.test.ts
@@ -0,0 +1,22 @@
+// The five levels of inertia, as the screen names them (ADR 0007).
+import { describe, expect, it } from 'vitest';
+import { en } from '../../src/lib/i18n/en';
+import { es } from '../../src/lib/i18n/es';
+import { fr } from '../../src/lib/i18n/fr';
+import { INERTIA_LEVELS } from '../../src/lib/types';
+
+describe('five levels of inertia', () => {
+  it('go from 1 to 5, 3 in the middle', () => {
+    expect(INERTIA_LEVELS).toEqual([1, 2, 3, 4, 5]);
+  });
+  it('each level has its own short name, in the three languages', () => {
+    expect(INERTIA_LEVELS.map((k) => fr[`inertia.name.${k}`])).toEqual(['très basse', 'basse', 'moyenne', 'haute', 'très haute']);
+    expect(INERTIA_LEVELS.map((k) => en[`inertia.name.${k}`])).toEqual(['very low', 'low', 'medium', 'high', 'very high']);
+    expect(INERTIA_LEVELS.map((k) => es[`inertia.name.${k}`])).toEqual(['muy baja', 'baja', 'media', 'alta', 'muy alta']);
+  });
+  it('a change of inertia is said to be voted at the level of the article, no longer one above', () => {
+    for (const cat of [fr, en, es]) expect(cat['inertia.change.note']).toContain('{level}');
+    expect(fr['inertia.change.note']).toContain("à l'inertie de l'article");
+    expect(fr['inertia.change.note']).not.toContain('au-dessus');
+  });
+});
diff --git a/web/tests/unit/versions.test.ts b/web/tests/unit/versions.test.ts
index 842b2b2..e8fa69b 100644
--- a/web/tests/unit/versions.test.ts
+++ b/web/tests/unit/versions.test.ts
@@ -8,13 +8,13 @@ function prop(id: string, unitId: string, over: Partial<Proposal> = {}): Proposa
     label: null, author: null, mine: false, revision: 1, createdAt: '', updatedAt: '', submittedAt: null, enteredAt: null,
     confirmedAt: null, seedMinimal: false, tally: { for: 0, against: 0 },
     evaluation: { cast: 0, required: 50, reached: false, missing: 50, requiredRatio: 1, wellRated: false },
-    votedAtInertia: 'standard', blocked: false, signals: 0, myVote: null, myVoteStale: false, translations: {},
+    votedAtInertia: 3, blocked: false, signals: 0, myVote: null, myVoteStale: false, translations: {},
     ...over,
   };
 }
 
 function unit(id: string, proposals: Proposal[]): Unit {
-  return { id, code: id, section: null, position: 0, inertia: 'standard', inForce: null, proposals };
+  return { id, code: id, section: null, position: 0, inertia: 3, inertiaChanges: [], inForce: null, proposals };
 }
 
 /** The reader's list: every open proposal, unit by unit, in document order. */