diff --git a/apps/web/src/pages/ReaderPage.tsx b/apps/web/src/pages/ReaderPage.tsx
index 718d337..d4ce3c6 100644
--- a/apps/web/src/pages/ReaderPage.tsx
+++ b/apps/web/src/pages/ReaderPage.tsx
@@ -5,7 +5,8 @@ import { CbzReader } from "../reader/CbzReader";
 import { EpubReader } from "../reader/EpubReader";
 import { pageLocator, parseCbrPageLocator, parseCbzPageLocator, parsePdfPageLocator, pdfPagePercent } from "../reader/locators";
 import { PdfReader } from "../reader/PdfReader";
-import { ReaderShell, type ReaderControls } from "../reader/ReaderShell";
+import { ReaderShell, type ReaderControls, type ReaderZoomControls } from "../reader/ReaderShell";
+import { clampReaderZoom, READER_ZOOM_DEFAULT, READER_ZOOM_STEP } from "../reader/readerLayout";
 import { useReaderProgress } from "../reader/useReaderProgress";
 
 const idleControls: ReaderControls = {
@@ -21,6 +22,7 @@ export function ReaderPage({ bookId }: { bookId: number }) {
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState<string>();
   const [page, setPage] = useState(1);
+  const [zoom, setZoom] = useState(READER_ZOOM_DEFAULT);
   const [readerControls, setReaderControls] = useState<ReaderControls>(idleControls);
   const { progress, error: progressError, save, queueSave } = useReaderProgress(bookId);
 
@@ -44,6 +46,7 @@ export function ReaderPage({ bookId }: { bookId: number }) {
 
   useEffect(() => {
     setReaderControls(idleControls);
+    setZoom(READER_ZOOM_DEFAULT);
   }, [bookId]);
 
   useEffect(() => {
@@ -77,6 +80,34 @@ export function ReaderPage({ bookId }: { bookId: number }) {
   );
 
   const readerError = error ?? progressError;
+  const supportsZoom = book?.format === "pdf" || book?.format === "cbz" || book?.format === "cbr";
+  const changeZoom = useCallback((nextZoom: number | ((currentZoom: number) => number)) => {
+    const stage = document.querySelector(".reader-stage") as HTMLElement | null;
+    const scrollRatioX = stage && stage.scrollWidth > stage.clientWidth ? (stage.scrollLeft + stage.clientWidth / 2) / stage.scrollWidth : 0.5;
+    const scrollRatioY = stage && stage.scrollHeight > stage.clientHeight ? (stage.scrollTop + stage.clientHeight / 2) / stage.scrollHeight : 0.5;
+
+    setZoom((currentZoom) => clampReaderZoom(typeof nextZoom === "function" ? nextZoom(currentZoom) : nextZoom));
+
+    requestAnimationFrame(() => {
+      requestAnimationFrame(() => {
+        if (!stage) return;
+        stage.scrollLeft = Math.max(0, stage.scrollWidth * scrollRatioX - stage.clientWidth / 2);
+        stage.scrollTop = Math.max(0, stage.scrollHeight * scrollRatioY - stage.clientHeight / 2);
+      });
+    });
+  }, []);
+  const zoomControls = useMemo<ReaderZoomControls | undefined>(
+    () =>
+      supportsZoom
+        ? {
+            zoom,
+            onZoomOut: () => changeZoom((currentZoom) => currentZoom - READER_ZOOM_STEP),
+            onZoomIn: () => changeZoom((currentZoom) => currentZoom + READER_ZOOM_STEP),
+            onZoomReset: () => changeZoom(READER_ZOOM_DEFAULT)
+          }
+        : undefined,
+    [changeZoom, supportsZoom, zoom]
+  );
 
   return (
     <ReaderShell
@@ -85,6 +116,7 @@ export function ReaderPage({ bookId }: { bookId: number }) {
       error={readerError}
       onRetry={error ? () => void loadBook() : undefined}
       controls={readerControls}
+      zoomControls={zoomControls}
     >
       {!book ? (
         <div className="reader-fallback">
@@ -98,6 +130,7 @@ export function ReaderPage({ bookId }: { bookId: number }) {
           url={fileUrl}
           page={page}
           backHref={backHref}
+          zoom={zoom}
           onPageCommit={savePdfPage}
           onControlsChange={setReaderControls}
         />
@@ -105,6 +138,7 @@ export function ReaderPage({ bookId }: { bookId: number }) {
         <CbzReader
           bookId={book.id}
           page={page}
+          zoom={zoom}
           onPageCommit={saveComicPage}
           onControlsChange={setReaderControls}
         />
diff --git a/apps/web/src/reader/CbzReader.tsx b/apps/web/src/reader/CbzReader.tsx
index e3a9870..e173504 100644
--- a/apps/web/src/reader/CbzReader.tsx
+++ b/apps/web/src/reader/CbzReader.tsx
@@ -1,7 +1,7 @@
 import { useCallback, useEffect, useRef, useState } from "react";
 import { api } from "../api/client";
 import type { CbzPagesDto } from "../api/types";
-import { clampReaderPage, orientedContainPageSize, readableViewportSize, readerPositionLabel, type ReaderSize } from "./readerLayout";
+import { clampReaderPage, orientedContainPageSize, readableViewportSize, readerPositionLabel, zoomReaderSize, type ReaderSize } from "./readerLayout";
 import type { ReaderControls } from "./ReaderShell";
 
 type PageCommitStrategy = "immediate" | "queued";
@@ -9,11 +9,13 @@ type PageCommitStrategy = "immediate" | "queued";
 export function CbzReader({
   bookId,
   page,
+  zoom,
   onPageCommit,
   onControlsChange
 }: {
   bookId: number;
   page: number;
+  zoom: number;
   onPageCommit: (page: number, pages: number, anchor?: number, strategy?: PageCommitStrategy) => void;
   onControlsChange: (controls: ReaderControls) => void;
 }) {
@@ -50,7 +52,7 @@ export function CbzReader({
   const pageCount = pages?.pageCount ?? 1;
   const currentPage = clampReaderPage(page, pageCount);
   const currentName = pages?.pages.find((item) => item.page === currentPage)?.name;
-  const fittedSize = viewportSize && imageSize ? orientedContainPageSize(viewportSize, imageSize) : null;
+  const fittedSize = viewportSize && imageSize ? zoomReaderSize(orientedContainPageSize(viewportSize, imageSize), zoom) : null;
   const imageStyle = fittedSize ? { width: `${fittedSize.width}px`, height: `${fittedSize.height}px` } : undefined;
 
   const go = useCallback(
diff --git a/apps/web/src/reader/PdfReader.tsx b/apps/web/src/reader/PdfReader.tsx
index d062a8b..77e209b 100644
--- a/apps/web/src/reader/PdfReader.tsx
+++ b/apps/web/src/reader/PdfReader.tsx
@@ -4,7 +4,7 @@ import { ReaderError } from "./ReaderError";
 import { pdfDocumentOptions } from "./pdfDocumentOptions";
 import { classifyPdfCanvas, pdfCanvasVisible, pdfRenderScale, pdfSentinelBackground, type PdfRenderResult } from "./pdfRender";
 import { configurePdfWorker } from "./pdfWorker";
-import { clampReaderPage, readableViewportSize, readerPositionLabel, type ReaderSize } from "./readerLayout";
+import { clampReaderPage, readableViewportSize, readerPositionLabel, readerZoomFactor, type ReaderSize } from "./readerLayout";
 import type { ReaderControls } from "./ReaderShell";
 
 configurePdfWorker(pdfjs);
@@ -15,6 +15,7 @@ type PdfReaderProps = {
   url: string;
   page: number;
   backHref: string;
+  zoom: number;
   onPageCommit: (page: number, pages: number, anchor?: number, strategy?: PageCommitStrategy) => void;
   onControlsChange: (controls: ReaderControls) => void;
 };
@@ -59,7 +60,7 @@ function afterNextPaint() {
   return new Promise<void>((resolve) => requestAnimationFrame(() => resolve()));
 }
 
-export function PdfReader({ url, page, backHref, onPageCommit, onControlsChange }: PdfReaderProps) {
+export function PdfReader({ url, page, backHref, zoom, onPageCommit, onControlsChange }: PdfReaderProps) {
   const frameRef = useRef<HTMLDivElement>(null);
   const canvasRef = useRef<HTMLCanvasElement>(null);
   const [documentProxy, setDocumentProxy] = useState<pdfjs.PDFDocumentProxy | null>(null);
@@ -206,7 +207,8 @@ export function PdfReader({ url, page, backHref, onPageCommit, onControlsChange
         const baseViewport = pdfPage.getViewport({ scale: 1 });
         const fitScale = pdfRenderScale(readerViewport, { width: baseViewport.width, height: baseViewport.height });
         const pixelRatio = Math.min(2, window.devicePixelRatio || 1);
-        const renderScale = Math.max(0.25, Math.min(3, fitScale)) * pixelRatio;
+        const zoomedScale = fitScale * readerZoomFactor(zoom);
+        const renderScale = Math.max(0.25, zoomedScale) * pixelRatio;
         const viewport = pdfPage.getViewport({ scale: renderScale });
         const cssWidth = Math.floor(viewport.width / pixelRatio);
         const cssHeight = Math.floor(viewport.height / pixelRatio);
@@ -287,7 +289,7 @@ export function PdfReader({ url, page, backHref, onPageCommit, onControlsChange
       cancelled = true;
       renderTask?.cancel();
     };
-  }, [currentPage, documentProxy, pageAttempt, viewportSize]);
+  }, [currentPage, documentProxy, pageAttempt, viewportSize, zoom]);
 
   if (documentError) {
     return (
diff --git a/apps/web/src/reader/ReaderShell.tsx b/apps/web/src/reader/ReaderShell.tsx
index b53d269..e132dbd 100644
--- a/apps/web/src/reader/ReaderShell.tsx
+++ b/apps/web/src/reader/ReaderShell.tsx
@@ -2,6 +2,7 @@ import { ArrowLeft, ArrowRight } from "lucide-react";
 import { useEffect, type ReactNode } from "react";
 import { ErrorRibbon } from "../components/ui";
 import { navigate } from "../router";
+import { readerZoomLabel, READER_ZOOM_DEFAULT, READER_ZOOM_MAX, READER_ZOOM_MIN } from "./readerLayout";
 
 export type ReaderControls = {
   canPrevious: boolean;
@@ -11,12 +12,20 @@ export type ReaderControls = {
   onNext: () => void;
 };
 
+export type ReaderZoomControls = {
+  zoom: number;
+  onZoomOut: () => void;
+  onZoomIn: () => void;
+  onZoomReset: () => void;
+};
+
 type ReaderShellProps = {
   title: string;
   backHref: string;
   error?: string;
   onRetry?: () => void;
   controls: ReaderControls;
+  zoomControls?: ReaderZoomControls;
   children: ReactNode;
 };
 
@@ -26,7 +35,7 @@ function isFormField(target: EventTarget | null) {
   return Boolean(element?.isContentEditable || tagName === "input" || tagName === "textarea" || tagName === "select");
 }
 
-export function ReaderShell({ title, backHref, error, onRetry, controls, children }: ReaderShellProps) {
+export function ReaderShell({ title, backHref, error, onRetry, controls, zoomControls, children }: ReaderShellProps) {
   useEffect(() => {
     const handleKeyDown = (event: KeyboardEvent) => {
       if (isFormField(event.target)) return;
@@ -60,6 +69,20 @@ export function ReaderShell({ title, backHref, error, onRetry, controls, childre
           Suivant
           <ArrowRight size={16} />
         </button>
+        {zoomControls && (
+          <div className="reader-zoom-controls" aria-label="Zoom du lecteur">
+            <button className="ghost-button reader-zoom-button" onClick={zoomControls.onZoomOut} disabled={zoomControls.zoom <= READER_ZOOM_MIN} aria-label="Reduire le zoom">
+              -
+            </button>
+            <span className="reader-zoom-label">{readerZoomLabel(zoomControls.zoom)}</span>
+            <button className="ghost-button reader-zoom-button" onClick={zoomControls.onZoomIn} disabled={zoomControls.zoom >= READER_ZOOM_MAX} aria-label="Augmenter le zoom">
+              +
+            </button>
+            <button className="ghost-button reader-zoom-reset" onClick={zoomControls.onZoomReset} disabled={zoomControls.zoom === READER_ZOOM_DEFAULT}>
+              Réinitialiser
+            </button>
+          </div>
+        )}
       </header>
       {error && (
         <div className="reader-status">
diff --git a/apps/web/src/reader/readerLayout.ts b/apps/web/src/reader/readerLayout.ts
index 5a5ae1f..b02315f 100644
--- a/apps/web/src/reader/readerLayout.ts
+++ b/apps/web/src/reader/readerLayout.ts
@@ -3,6 +3,24 @@ export type ReaderSize = {
   height: number;
 };
 
+export const READER_ZOOM_MIN = 50;
+export const READER_ZOOM_MAX = 300;
+export const READER_ZOOM_STEP = 25;
+export const READER_ZOOM_DEFAULT = 100;
+
+export function clampReaderZoom(zoom: number) {
+  const steppedZoom = Math.round(zoom / READER_ZOOM_STEP) * READER_ZOOM_STEP;
+  return Math.max(READER_ZOOM_MIN, Math.min(steppedZoom, READER_ZOOM_MAX));
+}
+
+export function readerZoomLabel(zoom: number) {
+  return `${clampReaderZoom(zoom)} %`;
+}
+
+export function readerZoomFactor(zoom: number) {
+  return clampReaderZoom(zoom) / 100;
+}
+
 export function clampReaderPage(page: number, pageCount: number) {
   const safePageCount = Math.max(1, Math.floor(pageCount));
   return Math.max(1, Math.min(Math.floor(page), safePageCount));
@@ -45,6 +63,14 @@ export function orientedContainPageSize(viewport: ReaderSize, page: ReaderSize):
   };
 }
 
+export function zoomReaderSize(size: ReaderSize, zoom: number): ReaderSize {
+  const factor = readerZoomFactor(zoom);
+  return {
+    width: Math.max(1, Math.floor(size.width * factor)),
+    height: Math.max(1, Math.floor(size.height * factor))
+  };
+}
+
 export function readableViewportSize(size: ReaderSize): ReaderSize | null {
   if (size.width < 32 || size.height < 32) return null;
   return {
diff --git a/apps/web/src/reader/readerRuntime.test.ts b/apps/web/src/reader/readerRuntime.test.ts
index dedbb19..b2c442a 100644
--- a/apps/web/src/reader/readerRuntime.test.ts
+++ b/apps/web/src/reader/readerRuntime.test.ts
@@ -1,7 +1,19 @@
 import { describe, expect, it } from "vitest";
 import { epubFileName } from "./EpubReader";
 import { pdfDocumentOptions } from "./pdfDocumentOptions";
-import { clampReaderPage, containPageSize, nextReaderPage, orientedContainPageSize, previousReaderPage, readableViewportSize, readerPositionLabel } from "./readerLayout";
+import {
+  clampReaderPage,
+  clampReaderZoom,
+  containPageSize,
+  nextReaderPage,
+  orientedContainPageSize,
+  previousReaderPage,
+  readableViewportSize,
+  readerPositionLabel,
+  readerZoomFactor,
+  readerZoomLabel,
+  zoomReaderSize
+} from "./readerLayout";
 import { classifyPdfCanvas, pdfCanvasHasVisibleContent, pdfCanvasVisible, pdfRenderScale } from "./pdfRender";
 import { configurePdfWorker, pdfWorkerSrc } from "./pdfWorker";
 import { readerErrorMessage } from "./ReaderError";
@@ -118,6 +130,20 @@ describe("reader runtime helpers", () => {
     expect(orientedContainPageSize({ width: 500, height: 900 }, { width: 1200, height: 900 })).toEqual({ width: 500, height: 375 });
   });
 
+  it("clamps reader zoom to 25 percent steps between 50 and 300", () => {
+    expect(clampReaderZoom(20)).toBe(50);
+    expect(clampReaderZoom(63)).toBe(75);
+    expect(clampReaderZoom(186)).toBe(175);
+    expect(clampReaderZoom(340)).toBe(300);
+    expect(readerZoomLabel(125)).toBe("125 %");
+    expect(readerZoomFactor(175)).toBe(1.75);
+  });
+
+  it("applies reader zoom above the contained media size", () => {
+    expect(zoomReaderSize({ width: 800, height: 600 }, 50)).toEqual({ width: 400, height: 300 });
+    expect(zoomReaderSize({ width: 800, height: 600 }, 200)).toEqual({ width: 1600, height: 1200 });
+  });
+
   it("ignores unusable reader viewport measurements", () => {
     expect(readableViewportSize({ width: 0, height: 833 })).toBeNull();
     expect(readableViewportSize({ width: 1, height: 1 })).toBeNull();
diff --git a/apps/web/src/styles/app.css b/apps/web/src/styles/app.css
index eee1a99..716eda6 100644
--- a/apps/web/src/styles/app.css
+++ b/apps/web/src/styles/app.css
@@ -890,6 +890,27 @@ main.app-main-reader .reader-page {
   background: rgba(38, 26, 18, 0.84);
 }
 
+.reader-zoom-controls {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  flex: 0 0 auto;
+}
+
+.reader-zoom-button {
+  width: 34px;
+  min-width: 34px;
+  padding: 0;
+  font-weight: 800;
+}
+
+.reader-zoom-label {
+  min-width: 58px;
+  color: var(--ink-muted);
+  text-align: center;
+  white-space: nowrap;
+}
+
 .reader-title {
   flex: 1 1 auto;
   overflow: hidden;
@@ -928,17 +949,16 @@ main.app-main-reader .reader-page {
   min-height: 0;
   min-width: 0;
   padding: 0;
-  overflow: hidden;
+  overflow: auto;
 }
 
 .reader-content {
   display: grid;
   place-items: center;
-  min-height: 0;
-  min-width: 0;
-  width: 100%;
-  height: 100%;
-  overflow: hidden;
+  min-width: 100%;
+  min-height: 100%;
+  width: max-content;
+  height: max-content;
 }
 
 .pdf-reader,
@@ -946,10 +966,8 @@ main.app-main-reader .reader-page {
 .cbz-reader {
   display: grid;
   place-items: center;
-  min-height: 0;
-  min-width: 0;
-  width: 100%;
-  height: 100%;
+  min-width: 100%;
+  min-height: 100%;
 }
 
 .epub-host {
@@ -978,9 +996,10 @@ main.app-main-reader .reader-page {
 .comic-page-frame {
   display: grid;
   place-items: center;
-  width: 100%;
-  height: 100%;
-  min-height: 64px;
+  width: max-content;
+  height: max-content;
+  min-width: 100%;
+  min-height: max(64px, 100%);
   margin: 0;
 }
 
@@ -989,8 +1008,6 @@ main.app-main-reader .reader-page {
   display: block;
   width: auto;
   height: auto;
-  max-width: 100%;
-  max-height: 100%;
   box-sizing: border-box;
   border: 1px solid var(--line);
   border-radius: var(--radius);
@@ -998,11 +1015,6 @@ main.app-main-reader .reader-page {
   object-fit: contain;
 }
 
-.cbz-reader img {
-  max-width: 100%;
-  max-height: 100%;
-}
-
 .reader-fallback {
   display: flex;
   flex-wrap: wrap;
@@ -1161,6 +1173,10 @@ main.app-main-reader .reader-page {
     gap: 8px;
   }
 
+  .reader-zoom-reset {
+    display: none;
+  }
+
   .epub-host {
     width: 100%;
   }