diff --git a/desktop/src/features/settings/ui/AppearanceSettingsControls.tsx b/desktop/src/features/settings/ui/AppearanceSettingsControls.tsx
index c37ba8f259..bd7113a461 100644
--- a/desktop/src/features/settings/ui/AppearanceSettingsControls.tsx
+++ b/desktop/src/features/settings/ui/AppearanceSettingsControls.tsx
@@ -20,6 +20,12 @@ import {
   useConversationDensity,
   type ConversationDensity,
 } from "@/shared/lib/conversationDensityPreference";
+import {
+  previewConversationFontSize,
+  setConversationFontSize,
+  useConversationFontSize,
+  type ConversationFontSize,
+} from "@/shared/lib/conversationFontSizePreference";
 import {
   ACCENT_COLORS,
   DEFAULT_GLASS_OPACITY,
@@ -105,6 +111,24 @@ const CONVERSATION_DENSITY_OPTIONS: readonly {
   },
 ];
 
+const CONVERSATION_FONT_SIZE_OPTIONS: readonly {
+  value: ConversationFontSize;
+  label: string;
+}[] = [
+  {
+    value: "smaller",
+    label: "Smaller",
+  },
+  {
+    value: "default",
+    label: "Default",
+  },
+  {
+    value: "larger",
+    label: "Larger",
+  },
+];
+
 function ConversationDensityPreviewMessage({
   avatar,
   author,
@@ -138,18 +162,18 @@ function ConversationDensityPreviewMessage({
   );
 }
 
-function ConversationDensityPreview() {
+function ConversationPreview() {
   return (
-    <div className="px-4 py-3" data-testid="conversation-density-preview">
+    <div className="px-4 py-3" data-testid="conversation-preview">
       <div
         aria-hidden="true"
         className="relative overflow-hidden rounded-xl border border-border/65 bg-muted/45"
-        data-testid="conversation-density-preview-surface"
+        data-testid="conversation-preview-surface"
       >
         <span className="absolute right-3 top-3 inline-flex rounded-full border border-border/65 bg-background/70 px-2.5 py-1 text-xs font-medium text-muted-foreground">
           Preview
         </span>
-        <div className="p-4" data-testid="conversation-density-preview-content">
+        <div className="p-4" data-testid="conversation-preview-content">
           <ConversationDensityPreviewMessage
             avatar="M"
             author="Maya"
@@ -176,12 +200,34 @@ function ConversationDensityPreview() {
   );
 }
 
-/** Message sizing and spacing shared by every conversation surface. */
-export function ConversationDensitySetting() {
+/** Independent message type and spacing controls shared by every conversation. */
+export function ConversationDisplaySettings() {
   const density = useConversationDensity();
+  const fontSize = useConversationFontSize();
 
   return (
     <>
+      <SettingsOptionRow data-testid="conversation-font-size-row">
+        <div className="min-w-0">
+          <p className="text-sm font-medium">Font size</p>
+          <p
+            className="text-sm font-normal text-muted-foreground/70"
+            data-settings-subcopy
+          >
+            Adjust message text and line height.
+          </p>
+        </div>
+        <SettingsSegmentedControl
+          className="w-72"
+          legend="Font size"
+          onPreviewChange={previewConversationFontSize}
+          onValueChange={setConversationFontSize}
+          optionTestIdPrefix="conversation-font-size"
+          options={CONVERSATION_FONT_SIZE_OPTIONS}
+          testId="conversation-font-size-control"
+          value={fontSize}
+        />
+      </SettingsOptionRow>
       <SettingsOptionRow data-testid="conversation-density-row">
         <div className="min-w-0">
           <p className="text-sm font-medium">Conversation density</p>
@@ -189,7 +235,7 @@ export function ConversationDensitySetting() {
             className="text-sm font-normal text-muted-foreground/70"
             data-settings-subcopy
           >
-            Adjust message size and spacing.
+            Adjust message and paragraph spacing.
           </p>
         </div>
         <SettingsSegmentedControl
@@ -203,7 +249,7 @@ export function ConversationDensitySetting() {
           value={density}
         />
       </SettingsOptionRow>
-      <ConversationDensityPreview />
+      <ConversationPreview />
     </>
   );
 }
diff --git a/desktop/src/features/settings/ui/SettingsPanels.tsx b/desktop/src/features/settings/ui/SettingsPanels.tsx
index 4896c207b1..094e021a9b 100644
--- a/desktop/src/features/settings/ui/SettingsPanels.tsx
+++ b/desktop/src/features/settings/ui/SettingsPanels.tsx
@@ -55,7 +55,7 @@ import {
 import { appearanceCommunityLabel } from "../lib/appearanceScopeCopy";
 import {
   AccentPickerContent,
-  ConversationDensitySetting,
+  ConversationDisplaySettings,
   GlassBackgroundSetting,
   LinkPreviewStyleSetting,
   ProminentActiveTabSetting,
@@ -782,7 +782,7 @@ function ThemeSettingsCard() {
           data-testid="appearance-preferences-card"
           title="Preferences"
         >
-          <ConversationDensitySetting />
+          <ConversationDisplaySettings />
           <LinkPreviewStyleSetting />
           <ThreadLayoutSetting />
         </SettingsOptionGroup>
diff --git a/desktop/src/main.tsx b/desktop/src/main.tsx
index 91b002eefc..6fc0028380 100644
--- a/desktop/src/main.tsx
+++ b/desktop/src/main.tsx
@@ -21,6 +21,7 @@ import { TooltipProvider } from "@/shared/ui/tooltip";
 import { recoverLocalStorageQuotaOnStartup } from "@/shared/lib/localStorageQuota";
 import { startLocalStorageSweep } from "@/shared/lib/localStorageSweep";
 import { initializeConversationDensityPreference } from "@/shared/lib/conversationDensityPreference";
+import { initializeConversationFontSizePreference } from "@/shared/lib/conversationFontSizePreference";
 
 type E2eWindow = Window & {
   __BUZZ_E2E__?: unknown;
@@ -126,6 +127,7 @@ async function bootstrap() {
   configureDevE2eBridgeFromUrl();
   recoverLocalStorageQuotaOnStartup();
   initializeConversationDensityPreference();
+  initializeConversationFontSizePreference();
   startLocalStorageSweep();
   await installE2eBridgeIfConfigured();
   await migrateLegacyCommunityStorageBeforeRender();
diff --git a/desktop/src/shared/lib/conversationDensityPreference.ts b/desktop/src/shared/lib/conversationDensityPreference.ts
index 5477b80626..302bce565d 100644
--- a/desktop/src/shared/lib/conversationDensityPreference.ts
+++ b/desktop/src/shared/lib/conversationDensityPreference.ts
@@ -1,6 +1,6 @@
 import * as React from "react";
 
-/** Device-level message sizing and spacing used across conversation surfaces. */
+/** Device-level spacing used across conversation surfaces. */
 export type ConversationDensity = "compact" | "comfortable" | "spacious";
 
 export const CONVERSATION_DENSITY_STORAGE_KEY =
diff --git a/desktop/src/shared/lib/conversationFontSizePreference.test.mjs b/desktop/src/shared/lib/conversationFontSizePreference.test.mjs
new file mode 100644
index 0000000000..d1d8ec602d
--- /dev/null
+++ b/desktop/src/shared/lib/conversationFontSizePreference.test.mjs
@@ -0,0 +1,56 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+const values = new Map();
+const attributes = new Map();
+
+globalThis.localStorage = {
+  getItem: (key) => values.get(key) ?? null,
+  setItem: (key, value) => values.set(key, String(value)),
+};
+globalThis.document = {
+  documentElement: {
+    setAttribute: (name, value) => attributes.set(name, value),
+  },
+};
+
+const preference = await import("./conversationFontSizePreference.ts");
+
+test("defaults invalid and missing conversation font sizes to default", () => {
+  assert.equal(preference.parseConversationFontSize(null), "default");
+  assert.equal(preference.parseConversationFontSize("medium"), "default");
+  assert.equal(preference.parseConversationFontSize("smaller"), "smaller");
+  assert.equal(preference.parseConversationFontSize("default"), "default");
+  assert.equal(preference.parseConversationFontSize("larger"), "larger");
+});
+
+test("persists and applies the selected conversation font size", () => {
+  preference.setConversationFontSize("smaller");
+  assert.equal(preference.getConversationFontSize(), "smaller");
+  assert.equal(
+    values.get(preference.CONVERSATION_FONT_SIZE_STORAGE_KEY),
+    "smaller",
+  );
+  assert.equal(attributes.get("data-conversation-font-size"), "smaller");
+});
+
+test("previews a font size without changing the saved preference", () => {
+  preference.setConversationFontSize("smaller");
+  preference.previewConversationFontSize("larger");
+  assert.equal(preference.getConversationFontSize(), "smaller");
+  assert.equal(
+    values.get(preference.CONVERSATION_FONT_SIZE_STORAGE_KEY),
+    "smaller",
+  );
+  assert.equal(attributes.get("data-conversation-font-size"), "larger");
+
+  preference.previewConversationFontSize(null);
+  assert.equal(attributes.get("data-conversation-font-size"), "smaller");
+});
+
+test("initializes from the stored conversation font size", () => {
+  values.set(preference.CONVERSATION_FONT_SIZE_STORAGE_KEY, "larger");
+  preference.initializeConversationFontSizePreference();
+  assert.equal(preference.getConversationFontSize(), "larger");
+  assert.equal(attributes.get("data-conversation-font-size"), "larger");
+});
diff --git a/desktop/src/shared/lib/conversationFontSizePreference.ts b/desktop/src/shared/lib/conversationFontSizePreference.ts
new file mode 100644
index 0000000000..6fb5fb2eab
--- /dev/null
+++ b/desktop/src/shared/lib/conversationFontSizePreference.ts
@@ -0,0 +1,84 @@
+import * as React from "react";
+
+/** Device-level text sizing used across conversation surfaces. */
+export type ConversationFontSize = "smaller" | "default" | "larger";
+
+export const CONVERSATION_FONT_SIZE_STORAGE_KEY =
+  "buzz.appearance.conversationFontSize";
+export const DEFAULT_CONVERSATION_FONT_SIZE: ConversationFontSize = "default";
+
+const listeners = new Set<() => void>();
+let conversationFontSize: ConversationFontSize = DEFAULT_CONVERSATION_FONT_SIZE;
+
+export function parseConversationFontSize(
+  value: string | null | undefined,
+): ConversationFontSize {
+  return value === "smaller" || value === "default" || value === "larger"
+    ? value
+    : DEFAULT_CONVERSATION_FONT_SIZE;
+}
+
+function readStoredConversationFontSize(): ConversationFontSize {
+  try {
+    return parseConversationFontSize(
+      globalThis.localStorage?.getItem(CONVERSATION_FONT_SIZE_STORAGE_KEY),
+    );
+  } catch {
+    return DEFAULT_CONVERSATION_FONT_SIZE;
+  }
+}
+
+function applyConversationFontSize(size: ConversationFontSize): void {
+  globalThis.document?.documentElement?.setAttribute(
+    "data-conversation-font-size",
+    size,
+  );
+}
+
+function notifyListeners(): void {
+  for (const listener of listeners) listener();
+}
+
+/** Apply the persisted preference before React renders to avoid a layout jump. */
+export function initializeConversationFontSizePreference(): void {
+  const nextSize = readStoredConversationFontSize();
+  const changed = nextSize !== conversationFontSize;
+  conversationFontSize = nextSize;
+  applyConversationFontSize(nextSize);
+  if (changed) notifyListeners();
+}
+
+function subscribe(listener: () => void): () => void {
+  listeners.add(listener);
+  return () => listeners.delete(listener);
+}
+
+export function getConversationFontSize(): ConversationFontSize {
+  return conversationFontSize;
+}
+
+export function setConversationFontSize(size: ConversationFontSize): void {
+  conversationFontSize = size;
+  applyConversationFontSize(size);
+  try {
+    globalThis.localStorage?.setItem(CONVERSATION_FONT_SIZE_STORAGE_KEY, size);
+  } catch {
+    // Persistence is best-effort; the live preference still applies.
+  }
+  notifyListeners();
+}
+
+/** Temporarily apply a size without changing the saved preference. */
+export function previewConversationFontSize(
+  size: ConversationFontSize | null,
+): void {
+  applyConversationFontSize(size ?? conversationFontSize);
+}
+
+export function useConversationFontSize(): ConversationFontSize {
+  return React.useSyncExternalStore(
+    subscribe,
+    getConversationFontSize,
+    () => DEFAULT_CONVERSATION_FONT_SIZE,
+  );
+}
diff --git a/desktop/src/shared/styles/globals/theme.css b/desktop/src/shared/styles/globals/theme.css
index 91de1ed1e1..acd87d71f6 100644
--- a/desktop/src/shared/styles/globals/theme.css
+++ b/desktop/src/shared/styles/globals/theme.css
@@ -3,9 +3,9 @@
     /* Catppuccin Latte (mauve accent) */
     --radius: 0.625rem;
     /*
-     * Comfortable conversation rhythm for channels, DMs, threads, Inbox, and
-     * the composer. The Appearance preference overrides this complete scale
-     * below, while rem units keep Cmd +/- text scaling intact.
+     * Default conversation type and comfy spacing for channels, DMs, threads,
+     * Inbox, and the composer. Independent Appearance preferences override the
+     * two scales below, while rem units keep Cmd +/- text scaling intact.
      */
     --conversation-message-font-size: 0.9375rem;
     --conversation-message-line-height: 1.25rem;
@@ -80,25 +80,31 @@
   }
 
   :root[data-conversation-density="compact"] {
-    --conversation-message-font-size: 0.875rem;
-    --conversation-message-line-height: 1.1875rem;
-    --conversation-author-line-height: 1rem;
     --conversation-body-gap: 0rem;
     --conversation-row-padding-block: 0.25rem;
     --conversation-paragraph-gap: 0.375rem;
     --conversation-list-item-gap: 0.25rem;
-    --conversation-timestamp-font-size: 0.625rem;
-    --conversation-timestamp-line-height: 0.875rem;
   }
 
   :root[data-conversation-density="spacious"] {
-    --conversation-message-font-size: 1rem;
-    --conversation-message-line-height: 1.375rem;
-    --conversation-author-line-height: 1.125rem;
     --conversation-body-gap: 0.25rem;
     --conversation-row-padding-block: 0.5rem;
     --conversation-paragraph-gap: 0.625rem;
     --conversation-list-item-gap: 0.5rem;
+  }
+
+  :root[data-conversation-font-size="smaller"] {
+    --conversation-message-font-size: 0.875rem;
+    --conversation-message-line-height: 1.1875rem;
+    --conversation-author-line-height: 1rem;
+    --conversation-timestamp-font-size: 0.625rem;
+    --conversation-timestamp-line-height: 0.875rem;
+  }
+
+  :root[data-conversation-font-size="larger"] {
+    --conversation-message-font-size: 1rem;
+    --conversation-message-line-height: 1.375rem;
+    --conversation-author-line-height: 1.125rem;
     --conversation-timestamp-font-size: 0.75rem;
     --conversation-timestamp-line-height: 1.125rem;
   }
diff --git a/desktop/tailwind.config.js b/desktop/tailwind.config.js
index c663a2ac3b..18e9eae494 100644
--- a/desktop/tailwind.config.js
+++ b/desktop/tailwind.config.js
@@ -12,8 +12,8 @@ export default {
         "3xs": "0.5rem", // 8px — tiny glyphs / micro labels
         badge: "0.625rem", // 10px — compact status badges
         // Shared channel, DM, thread, and composer type. Backed by CSS
-        // variables so the Appearance preference can change the complete
-        // conversation rhythm without branching individual components.
+        // variables so font size and density can change independently without
+        // branching individual components.
         message: [
           "var(--conversation-message-font-size)",
           { lineHeight: "var(--conversation-message-line-height)" },
diff --git a/desktop/tests/e2e/buzz-theme-screenshots.spec.ts b/desktop/tests/e2e/buzz-theme-screenshots.spec.ts
index cd3a262648..75581205bd 100644
--- a/desktop/tests/e2e/buzz-theme-screenshots.spec.ts
+++ b/desktop/tests/e2e/buzz-theme-screenshots.spec.ts
@@ -9,6 +9,8 @@ const GLASS_BACKGROUND_STORAGE_KEY = "buzz-glass-background";
 const GLASS_OPACITY_STORAGE_KEY = "buzz-glass-opacity";
 const PROMINENT_ACTIVE_TAB_STORAGE_KEY = "buzz-prominent-active-tab";
 const CONVERSATION_DENSITY_STORAGE_KEY = "buzz.appearance.conversationDensity";
+const CONVERSATION_FONT_SIZE_STORAGE_KEY =
+  "buzz.appearance.conversationFontSize";
 const MOCK_PUBKEY = "deadbeef".repeat(8);
 const GENERAL_CHANNEL_ID = "9a1657ac-f7aa-5db0-b632-d8bbeb6dfb50";
 
@@ -617,7 +619,7 @@ test("appearance groups theme and preferences into labeled rows", async ({
   ).toBeLessThanOrEqual(0.5);
 });
 
-test("conversation density applies and persists all three scales", async ({
+test("conversation font size and density apply independently", async ({
   page,
 }) => {
   await seedTheme(page, "buzz");
@@ -625,27 +627,35 @@ test("conversation density applies and persists all three scales", async ({
   await openAppearance(page, "light");
 
   const root = page.locator("html");
-  const control = page.getByTestId("conversation-density-control");
+  const densityControl = page.getByTestId("conversation-density-control");
   const compact = page.getByTestId("conversation-density-compact");
   const comfortable = page.getByTestId("conversation-density-comfortable");
   const spacious = page.getByTestId("conversation-density-spacious");
-  const indicator = page.getByTestId("conversation-density-control-indicator");
-  const preview = page.getByTestId("conversation-density-preview");
-  const previewSurface = page.getByTestId(
-    "conversation-density-preview-surface",
+  const densityIndicator = page.getByTestId(
+    "conversation-density-control-indicator",
   );
-  const previewContent = page.getByTestId(
-    "conversation-density-preview-content",
+  const fontSizeControl = page.getByTestId("conversation-font-size-control");
+  const smaller = page.getByTestId("conversation-font-size-smaller");
+  const defaultSize = page.getByTestId("conversation-font-size-default");
+  const larger = page.getByTestId("conversation-font-size-larger");
+  const fontSizeIndicator = page.getByTestId(
+    "conversation-font-size-control-indicator",
   );
+  const preview = page.getByTestId("conversation-preview");
+  const previewSurface = page.getByTestId("conversation-preview-surface");
+  const previewContent = page.getByTestId("conversation-preview-content");
   const previewChip = preview.getByText("Preview");
   const firstPreviewMessage = previewSurface.locator("article").first();
   const previewMessage = preview.getByText(
     "The revised conversation layout is ready to review.",
   );
   const previewTimestamp = preview.getByText("9:41");
-  const description = page
+  const densityDescription = page
     .getByTestId("conversation-density-row")
     .locator("[data-settings-subcopy]");
+  const fontSizeDescription = page
+    .getByTestId("conversation-font-size-row")
+    .locator("[data-settings-subcopy]");
   const readScale = () =>
     root.evaluate((element) => {
       const style = window.getComputedStyle(element);
@@ -710,12 +720,21 @@ test("conversation density applies and persists all three scales", async ({
   await expect(
     page.getByRole("group", { name: "Conversation density" }),
   ).toBeVisible();
-  await expect(control).toHaveAccessibleName("Conversation density");
+  await expect(page.getByRole("group", { name: "Font size" })).toBeVisible();
+  await expect(densityControl).toHaveAccessibleName("Conversation density");
+  await expect(fontSizeControl).toHaveAccessibleName("Font size");
   await expect(comfortable).toHaveText("Comfy");
+  await expect(defaultSize).toHaveText("Default");
   await expect(preview).toContainText("Preview");
   await expect(preview).not.toContainText("Message #design");
   await expect(comfortable).toHaveAttribute("aria-pressed", "true");
-  await expect(description).toHaveText("Adjust message size and spacing.");
+  await expect(defaultSize).toHaveAttribute("aria-pressed", "true");
+  await expect(densityDescription).toHaveText(
+    "Adjust message and paragraph spacing.",
+  );
+  await expect(fontSizeDescription).toHaveText(
+    "Adjust message text and line height.",
+  );
   await expect.poll(readScale).toEqual({
     authorLineHeight: 1.0625,
     bodyGap: 0.125,
@@ -729,13 +748,18 @@ test("conversation density applies and persists all three scales", async ({
   await expect
     .poll(() =>
       Promise.all([
-        control.evaluate((element) => element.getBoundingClientRect().width),
+        densityControl.evaluate(
+          (element) => element.getBoundingClientRect().width,
+        ),
+        fontSizeControl.evaluate(
+          (element) => element.getBoundingClientRect().width,
+        ),
         page
           .getByTestId("appearance-color-mode-control")
           .evaluate((element) => element.getBoundingClientRect().width),
       ]),
     )
-    .toEqual([288, 240]);
+    .toEqual([288, 288, 240]);
   await expect
     .poll(() =>
       previewMessage.evaluate((element) => {
@@ -752,15 +776,17 @@ test("conversation density applies and persists all three scales", async ({
   });
   await expect.poll(readPreviewTimestampScale).toEqual(["11px", "16px"]);
   await expect.poll(readSettingsChromeScale).toEqual(["24px", "14px", "18px"]);
-  await expect(indicator).toHaveCSS("transition-duration", "0.2s");
-  await expect(indicator).toHaveCSS("transition-property", /transform/);
+  await expect(densityIndicator).toHaveCSS("transition-duration", "0.2s");
+  await expect(densityIndicator).toHaveCSS("transition-property", /transform/);
+  await expect(fontSizeIndicator).toHaveCSS("transition-duration", "0.2s");
+  await expect(fontSizeIndicator).toHaveCSS("transition-property", /transform/);
   await expect
     .poll(async () => {
       const [previewBackground, controlBackground] = await Promise.all([
         previewSurface.evaluate(
           (element) => window.getComputedStyle(element).backgroundColor,
         ),
-        control.evaluate(
+        densityControl.evaluate(
           (element) => window.getComputedStyle(element).backgroundColor,
         ),
       ]);
@@ -774,7 +800,7 @@ test("conversation density applies and persists all three scales", async ({
   expect(previewChipBox).not.toBeNull();
   expect(firstPreviewMessageBox).not.toBeNull();
   if (!previewSurfaceBox || !previewChipBox || !firstPreviewMessageBox) {
-    throw new Error("Conversation density preview geometry is missing");
+    throw new Error("Conversation preview geometry is missing");
   }
   const previewChipRightInset =
     previewSurfaceBox.x +
@@ -804,7 +830,7 @@ test("conversation density applies and persists all three scales", async ({
   await expect(previewChip).toHaveCSS("padding-top", "4px");
   await expect(previewChip).toHaveCSS("padding-bottom", "4px");
 
-  await indicator.evaluate((element) => {
+  await densityIndicator.evaluate((element) => {
     element.addEventListener(
       "transitionrun",
       () => element.setAttribute("data-transition-ran", "true"),
@@ -813,10 +839,10 @@ test("conversation density applies and persists all three scales", async ({
   });
 
   await compact.click();
-  await expect(indicator).toHaveAttribute("data-transition-ran", "true");
+  await expect(densityIndicator).toHaveAttribute("data-transition-ran", "true");
   await expect(root).toHaveAttribute("data-conversation-density", "compact");
+  await expect(root).toHaveAttribute("data-conversation-font-size", "default");
   await expect(compact).toHaveAttribute("aria-pressed", "true");
-  await expect(description).toHaveText("Adjust message size and spacing.");
   await expect
     .poll(() =>
       page.evaluate(
@@ -826,14 +852,14 @@ test("conversation density applies and persists all three scales", async ({
     )
     .toBe("compact");
   await expect.poll(readScale).toEqual({
-    authorLineHeight: 1,
+    authorLineHeight: 1.0625,
     bodyGap: 0,
-    fontSize: 0.875,
-    lineHeight: 1.1875,
+    fontSize: 0.9375,
+    lineHeight: 1.25,
     paragraphGap: 0.375,
     rowPadding: 0.25,
-    timestampFontSize: 0.625,
-    timestampLineHeight: 0.875,
+    timestampFontSize: 0.6875,
+    timestampLineHeight: 1,
   });
   await expect.poll(readSettingsScale).toEqual({
     fontSize: "14px",
@@ -841,17 +867,41 @@ test("conversation density applies and persists all three scales", async ({
     minHeight: "64px",
     paddingBlock: "12px",
   });
-  await expect.poll(readPreviewTimestampScale).toEqual(["10px", "14px"]);
+  await expect.poll(readPreviewTimestampScale).toEqual(["11px", "16px"]);
   await expect.poll(readSettingsChromeScale).toEqual(["24px", "14px", "18px"]);
+
+  await larger.click();
+  await expect(root).toHaveAttribute("data-conversation-density", "compact");
+  await expect(root).toHaveAttribute("data-conversation-font-size", "larger");
+  await expect(larger).toHaveAttribute("aria-pressed", "true");
+  await expect
+    .poll(() =>
+      page.evaluate(
+        (key) => window.localStorage.getItem(key),
+        CONVERSATION_FONT_SIZE_STORAGE_KEY,
+      ),
+    )
+    .toBe("larger");
+  await expect.poll(readScale).toEqual({
+    authorLineHeight: 1.125,
+    bodyGap: 0,
+    fontSize: 1,
+    lineHeight: 1.375,
+    paragraphGap: 0.375,
+    rowPadding: 0.25,
+    timestampFontSize: 0.75,
+    timestampLineHeight: 1.125,
+  });
+  await expect.poll(readPreviewTimestampScale).toEqual(["12px", "18px"]);
   await waitForAnimations(page);
   await page.getByTestId("appearance-preferences-card").screenshot({
-    path: `${SHOTS}/15-conversation-density-compact.png`,
+    path: `${SHOTS}/15-conversation-compact-larger.png`,
   });
 
   await spacious.click();
   await expect(root).toHaveAttribute("data-conversation-density", "spacious");
+  await expect(root).toHaveAttribute("data-conversation-font-size", "larger");
   await expect(spacious).toHaveAttribute("aria-pressed", "true");
-  await expect(description).toHaveText("Adjust message size and spacing.");
   await expect.poll(readScale).toEqual({
     authorLineHeight: 1.125,
     bodyGap: 0.25,
@@ -870,19 +920,36 @@ test("conversation density applies and persists all three scales", async ({
   });
   await expect.poll(readPreviewTimestampScale).toEqual(["12px", "18px"]);
   await expect.poll(readSettingsChromeScale).toEqual(["24px", "14px", "18px"]);
+
+  await smaller.click();
+  await expect(root).toHaveAttribute("data-conversation-density", "spacious");
+  await expect(root).toHaveAttribute("data-conversation-font-size", "smaller");
+  await expect(smaller).toHaveAttribute("aria-pressed", "true");
+  await expect.poll(readScale).toEqual({
+    authorLineHeight: 1,
+    bodyGap: 0.25,
+    fontSize: 0.875,
+    lineHeight: 1.1875,
+    paragraphGap: 0.625,
+    rowPadding: 0.5,
+    timestampFontSize: 0.625,
+    timestampLineHeight: 0.875,
+  });
+  await expect.poll(readPreviewTimestampScale).toEqual(["10px", "14px"]);
   await waitForAnimations(page);
   await page.getByTestId("appearance-preferences-card").screenshot({
-    path: `${SHOTS}/16-conversation-density-spacious.png`,
+    path: `${SHOTS}/16-conversation-spacious-smaller.png`,
   });
 
   await comfortable.click();
+  await defaultSize.click();
   await expect(root).toHaveAttribute(
     "data-conversation-density",
     "comfortable",
   );
   await expect(comfortable).toHaveAttribute("aria-pressed", "true");
 
-  const controlBox = await control.boundingBox();
+  const controlBox = await densityControl.boundingBox();
   const compactBox = await compact.boundingBox();
   const spaciousBox = await spacious.boundingBox();
   expect(controlBox).not.toBeNull();
@@ -901,6 +968,7 @@ test("conversation density applies and persists all three scales", async ({
     controlBox.y + controlBox.height / 2,
   );
   await expect(root).toHaveAttribute("data-conversation-density", "spacious");
+  await expect(root).toHaveAttribute("data-conversation-font-size", "default");
   await expect
     .poll(() =>
       page.evaluate(
@@ -909,14 +977,16 @@ test("conversation density applies and persists all three scales", async ({
       ),
     )
     .toBe("comfortable");
-  await expect
-    .poll(() =>
-      previewMessage.evaluate((element) => {
-        const style = window.getComputedStyle(element);
-        return [style.fontSize, style.lineHeight];
-      }),
-    )
-    .toEqual(["16px", "22px"]);
+  await expect.poll(readScale).toEqual({
+    authorLineHeight: 1.0625,
+    bodyGap: 0.25,
+    fontSize: 0.9375,
+    lineHeight: 1.25,
+    paragraphGap: 0.625,
+    rowPadding: 0.5,
+    timestampFontSize: 0.6875,
+    timestampLineHeight: 1,
+  });
   await expect.poll(readSettingsScale).toEqual({
     fontSize: "14px",
     lineHeight: "20px",
@@ -934,9 +1004,60 @@ test("conversation density applies and persists all three scales", async ({
     )
     .toBe("spacious");
   await comfortable.click();
+
+  const fontSizeControlBox = await fontSizeControl.boundingBox();
+  const smallerBox = await smaller.boundingBox();
+  const largerBox = await larger.boundingBox();
+  expect(fontSizeControlBox).not.toBeNull();
+  expect(smallerBox).not.toBeNull();
+  expect(largerBox).not.toBeNull();
+  if (!fontSizeControlBox || !smallerBox || !largerBox) {
+    throw new Error("Conversation font size control geometry is missing");
+  }
+  await page.mouse.move(
+    smallerBox.x + smallerBox.width / 2,
+    fontSizeControlBox.y + fontSizeControlBox.height / 2,
+  );
+  await page.mouse.down();
+  await page.mouse.move(
+    largerBox.x + largerBox.width / 2,
+    fontSizeControlBox.y + fontSizeControlBox.height / 2,
+  );
+  await expect(root).toHaveAttribute("data-conversation-font-size", "larger");
+  await expect(root).toHaveAttribute(
+    "data-conversation-density",
+    "comfortable",
+  );
+  await expect
+    .poll(() =>
+      page.evaluate(
+        (key) => window.localStorage.getItem(key),
+        CONVERSATION_FONT_SIZE_STORAGE_KEY,
+      ),
+    )
+    .toBe("default");
+  await expect
+    .poll(() =>
+      previewMessage.evaluate((element) => {
+        const style = window.getComputedStyle(element);
+        return [style.fontSize, style.lineHeight];
+      }),
+    )
+    .toEqual(["16px", "22px"]);
+  await page.mouse.up();
+  await expect(larger).toHaveAttribute("aria-pressed", "true");
+  await expect
+    .poll(() =>
+      page.evaluate(
+        (key) => window.localStorage.getItem(key),
+        CONVERSATION_FONT_SIZE_STORAGE_KEY,
+      ),
+    )
+    .toBe("larger");
+  await defaultSize.click();
   await waitForAnimations(page);
   await page.getByTestId("appearance-preferences-card").screenshot({
-    path: `${SHOTS}/14-conversation-density.png`,
+    path: `${SHOTS}/14-conversation-preferences.png`,
   });
 });
 
@@ -1352,6 +1473,8 @@ test("glass background keeps the content panel solid", async ({ page }) => {
   const matchingRadiusControls = [
     page.getByTestId("appearance-color-mode-control"),
     page.getByTestId("appearance-color-mode-indicator"),
+    page.getByTestId("conversation-font-size-control"),
+    page.getByTestId("conversation-font-size-control-indicator"),
     page.getByTestId("conversation-density-control"),
     page.getByTestId("conversation-density-control-indicator"),
     page.getByTestId("theme-style-trigger"),
diff --git a/desktop/tests/e2e/inbox-refactor-screenshots.spec.ts b/desktop/tests/e2e/inbox-refactor-screenshots.spec.ts
index 9a73d34e91..4e9ca8ca3b 100644
--- a/desktop/tests/e2e/inbox-refactor-screenshots.spec.ts
+++ b/desktop/tests/e2e/inbox-refactor-screenshots.spec.ts
@@ -427,6 +427,18 @@ test.describe("inbox refactor screenshots", () => {
     await page.locator("html").evaluate((root) => {
       root.setAttribute("data-conversation-density", "compact");
     });
+    await expect.poll(readConversationMetrics).toEqual([
+      { fontSize: "15px", lineHeight: "20px" },
+      { paddingBottom: "4px", paddingTop: "4px" },
+      { fontSize: "15px", lineHeight: "17px" },
+      { fontSize: "15px", lineHeight: "20px" },
+      { fontSize: "11px", lineHeight: "16px" },
+      { fontSize: "15px", lineHeight: "20px" },
+    ]);
+
+    await page.locator("html").evaluate((root) => {
+      root.setAttribute("data-conversation-font-size", "smaller");
+    });
     await expect.poll(readConversationMetrics).toEqual([
       { fontSize: "14px", lineHeight: "19px" },
       { paddingBottom: "4px", paddingTop: "4px" },
@@ -440,6 +452,7 @@ test.describe("inbox refactor screenshots", () => {
 
     await page.locator("html").evaluate((root) => {
       root.setAttribute("data-conversation-density", "spacious");
+      root.setAttribute("data-conversation-font-size", "larger");
     });
     await expect.poll(readConversationMetrics).toEqual([
       { fontSize: "16px", lineHeight: "22px" },
@@ -454,6 +467,7 @@ test.describe("inbox refactor screenshots", () => {
 
     await page.locator("html").evaluate((root) => {
       root.setAttribute("data-conversation-density", "comfortable");
+      root.setAttribute("data-conversation-font-size", "default");
     });
 
     await page.evaluate(() => {