diff --git a/public/index.php b/public/index.php
index 344e4f0..2b0915d 100644
--- a/public/index.php
+++ b/public/index.php
@@ -51,6 +51,7 @@ $router->get('/belege/{id}', fn($p) => (new BelegController())->show($p));
 $router->get('/belege/{id}/file', fn($p) => (new BelegController())->serveFile($p));
 $router->post('/belege/{id}/delete', fn($p) => (new BelegController())->destroy($p));
 $router->post('/belege/{id}/meta',   fn($p) => (new BelegController())->updateMeta($p));
+$router->post('/belege/{id}/crop',   fn($p) => (new BelegController())->cropImage($p));
 $router->post('/belege/{id}/vorschlag/generate', fn($p) => (new BelegController())->generateVorschlag($p));
 $router->post('/belege/{id}/vorschlag/reset',    fn($p) => (new BelegController())->resetVorschlag($p));
 
diff --git a/src/Controllers/BelegController.php b/src/Controllers/BelegController.php
index abaf4c4..8f8bec0 100644
--- a/src/Controllers/BelegController.php
+++ b/src/Controllers/BelegController.php
@@ -260,6 +260,58 @@ class BelegController
         View::redirect('/belege', 'Beleg gelöscht.');
     }
 
+    public function cropImage(array $params): void
+    {
+        header('Content-Type: application/json');
+        $id    = (int)$params['id'];
+        $beleg = Beleg::find($id);
+
+        if (!$beleg) {
+            http_response_code(404);
+            echo json_encode(['error' => 'Beleg nicht gefunden.']);
+            return;
+        }
+        if ($beleg['locked']) {
+            http_response_code(403);
+            echo json_encode(['error' => 'GoBD: Gesperrter Beleg kann nicht verändert werden.']);
+            return;
+        }
+        if (!in_array($beleg['mime_type'], ['image/jpeg', 'image/png'], true)) {
+            http_response_code(422);
+            echo json_encode(['error' => 'Zuschneiden nur für JPEG und PNG möglich.']);
+            return;
+        }
+
+        $body = json_decode(file_get_contents('php://input'), true) ?? [];
+        $x    = (int)($body['x'] ?? 0);
+        $y    = (int)($body['y'] ?? 0);
+        $w    = (int)($body['w'] ?? 0);
+        $h    = (int)($body['h'] ?? 0);
+
+        if ($w < 10 || $h < 10) {
+            http_response_code(422);
+            echo json_encode(['error' => 'Auswahlbereich zu klein (mindestens 10×10 Pixel).']);
+            return;
+        }
+
+        $absPath = dirname(__DIR__, 2) . '/public/' . $beleg['storage_path'];
+        if (!file_exists($absPath)) {
+            http_response_code(404);
+            echo json_encode(['error' => 'Datei nicht gefunden.']);
+            return;
+        }
+
+        $svc = new ImageCropService();
+        if (!$svc->cropToRect($absPath, $x, $y, $w, $h)) {
+            http_response_code(500);
+            echo json_encode(['error' => 'Zuschnitt fehlgeschlagen.']);
+            return;
+        }
+
+        Beleg::updateHash($id, hash_file('sha256', $absPath));
+        echo json_encode(['ok' => true]);
+    }
+
     private function renderView(string $template, array $data): string
     {
         extract($data, EXTR_SKIP);
diff --git a/src/Models/Beleg.php b/src/Models/Beleg.php
index 32a5f6f..03345ed 100644
--- a/src/Models/Beleg.php
+++ b/src/Models/Beleg.php
@@ -218,6 +218,14 @@ class Beleg
         );
     }
 
+    public static function updateHash(int $id, string $hash): void
+    {
+        Database::execute(
+            'UPDATE belege SET file_hash = ?, updated_at = NOW() WHERE id = ?',
+            [$hash, $id]
+        );
+    }
+
     public static function saveBelegText(int $id, string $text): void
     {
         Database::execute(
diff --git a/src/Services/ImageCropService.php b/src/Services/ImageCropService.php
index 239eeb7..679b895 100644
--- a/src/Services/ImageCropService.php
+++ b/src/Services/ImageCropService.php
@@ -10,6 +10,50 @@ class ImageCropService
     private const PADDING = 25;  // Pixel-Abstand, der nach dem Zuschnitt ringsum erhalten bleibt
     private const MIN_CROP_GAIN = 0.03; // Mindestens 3 % Einsparung, sonst kein Zuschnitt
 
+    /**
+     * Schneidet ein Bild auf den angegebenen Bereich zu (manueller Zuschnitt).
+     * Koordinaten und Maße beziehen sich auf das Originalbild in Pixeln.
+     * Gibt true zurück, wenn das Bild gespeichert wurde.
+     */
+    public function cropToRect(string $path, int $x, int $y, int $w, int $h): bool
+    {
+        $mime = mime_content_type($path);
+
+        $img = match ($mime) {
+            'image/jpeg' => imagecreatefromjpeg($path),
+            'image/png'  => imagecreatefrompng($path),
+            default      => null,
+        };
+
+        if (!$img instanceof \GdImage) {
+            return false;
+        }
+
+        $imgW = imagesx($img);
+        $imgH = imagesy($img);
+
+        // Koordinaten auf Bildgrenzen klemmen
+        $x = max(0, min($x, $imgW - 1));
+        $y = max(0, min($y, $imgH - 1));
+        $w = max(1, min($w, $imgW - $x));
+        $h = max(1, min($h, $imgH - $y));
+
+        $cropped = imagecrop($img, ['x' => $x, 'y' => $y, 'width' => $w, 'height' => $h]);
+        imagedestroy($img);
+
+        if (!$cropped instanceof \GdImage) {
+            return false;
+        }
+
+        $saved = match ($mime) {
+            'image/jpeg' => imagejpeg($cropped, $path, 92),
+            'image/png'  => imagepng($cropped, $path),
+        };
+
+        imagedestroy($cropped);
+        return $saved;
+    }
+
     /**
      * Schneidet weißen/hellen Rand eines JPEG- oder PNG-Bilds automatisch weg.
      * Gibt true zurück, wenn das Bild tatsächlich verändert wurde.
diff --git a/src/Views/belege/detail.php b/src/Views/belege/detail.php
index ee95d14..58be0ad 100644
--- a/src/Views/belege/detail.php
+++ b/src/Views/belege/detail.php
@@ -88,6 +88,9 @@ $suppliers = $suppliers ?? [];
         </div>
         <div style="margin-left:auto;display:flex;gap:.5rem">
             <a href="/belege/<?= $h($beleg['id']) ?>/file" target="_blank" class="btn btn-secondary btn-sm">Datei öffnen</a>
+            <?php if (!$beleg['locked'] && in_array($beleg['mime_type'], ['image/jpeg', 'image/png'])): ?>
+            <button type="button" class="btn btn-secondary btn-sm" onclick="openCropModal()">Zuschneiden</button>
+            <?php endif; ?>
             <?php if (!$beleg['locked']): ?>
             <button type="button" class="btn btn-secondary btn-sm"
                     onclick="document.getElementById('beleg-meta-form').style.display = document.getElementById('beleg-meta-form').style.display === 'none' ? 'block' : 'none'">
@@ -739,6 +742,175 @@ document.addEventListener('DOMContentLoaded', function () {
 </script>
 <?php endif; ?>
 
+<?php if (!$beleg['locked'] && in_array($beleg['mime_type'], ['image/jpeg', 'image/png'])): ?>
+<!-- Crop-Modal -->
+<div class="modal-overlay" id="crop-modal-overlay" style="display:none;align-items:center;justify-content:center">
+    <div class="modal" style="max-width:95vw;width:auto;padding:1.25rem">
+        <div class="modal-title" style="margin-bottom:.75rem">Beleg zuschneiden</div>
+        <p class="text-sm text-muted" style="margin-bottom:.75rem">
+            Ziehe einen Rahmen über den gewünschten Ausschnitt. Das Original wird unwiderruflich ersetzt.
+        </p>
+        <div id="crop-canvas-wrap" style="position:relative;display:inline-block;cursor:crosshair;line-height:0;border:1px solid var(--color-border);border-radius:var(--radius)">
+            <canvas id="crop-canvas"></canvas>
+        </div>
+        <div style="margin-top:.75rem;display:flex;gap:.5rem;align-items:center">
+            <button type="button" class="btn btn-primary btn-sm" id="crop-confirm-btn" disabled onclick="confirmCrop()">Zuschnitt übernehmen</button>
+            <button type="button" class="btn btn-secondary btn-sm" onclick="closeCropModal()">Abbrechen</button>
+            <span id="crop-size-hint" class="text-muted text-sm"></span>
+        </div>
+    </div>
+</div>
+
+<script>
+(function() {
+    const BELEG_ID   = <?= (int)$beleg['id'] ?>;
+    const FILE_URL   = '/belege/<?= (int)$beleg['id'] ?>/file';
+    const overlay    = document.getElementById('crop-modal-overlay');
+    const canvas     = document.getElementById('crop-canvas');
+    const confirmBtn = document.getElementById('crop-confirm-btn');
+    const sizeHint   = document.getElementById('crop-size-hint');
+    const ctx        = canvas.getContext('2d');
+
+    let img = null;
+    let scaleX = 1, scaleY = 1;
+    let sel = null;       // {x,y,w,h} in Canvas-Koordinaten
+    let dragging = false;
+    let startX = 0, startY = 0;
+
+    window.openCropModal = function() {
+        overlay.style.display = 'flex';
+        if (img) { drawCanvas(); return; }
+
+        img = new Image();
+        img.onload = function() {
+            // Canvas auf max. 90vw / 72vh skalieren
+            const maxW = Math.min(window.innerWidth  * 0.90, 1200);
+            const maxH = Math.min(window.innerHeight * 0.72, 900);
+            const ratio = Math.min(maxW / img.naturalWidth, maxH / img.naturalHeight, 1);
+            canvas.width  = Math.round(img.naturalWidth  * ratio);
+            canvas.height = Math.round(img.naturalHeight * ratio);
+            scaleX = img.naturalWidth  / canvas.width;
+            scaleY = img.naturalHeight / canvas.height;
+            sel = null;
+            drawCanvas();
+        };
+        img.src = FILE_URL + '?nocache=' + Date.now();
+    };
+
+    window.closeCropModal = function() {
+        overlay.style.display = 'none';
+    };
+
+    function drawCanvas() {
+        ctx.clearRect(0, 0, canvas.width, canvas.height);
+        ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
+        if (!sel || sel.w === 0 || sel.h === 0) return;
+
+        // Abdunkeln außerhalb der Auswahl
+        ctx.fillStyle = 'rgba(0,0,0,0.45)';
+        ctx.fillRect(0, 0, canvas.width, canvas.height);
+
+        // Ausschnitt freistellen
+        ctx.drawImage(img,
+            sel.x * scaleX, sel.y * scaleY, sel.w * scaleX, sel.h * scaleY,
+            sel.x, sel.y, sel.w, sel.h);
+
+        // Rahmen
+        ctx.strokeStyle = '#fff';
+        ctx.lineWidth   = 1.5;
+        ctx.setLineDash([5, 3]);
+        ctx.strokeRect(sel.x + 0.5, sel.y + 0.5, sel.w, sel.h);
+        ctx.setLineDash([]);
+
+        const realW = Math.round(sel.w * scaleX);
+        const realH = Math.round(sel.h * scaleY);
+        sizeHint.textContent = realW + ' × ' + realH + ' px';
+        confirmBtn.disabled  = (realW < 10 || realH < 10);
+    }
+
+    function canvasPos(e) {
+        const r = canvas.getBoundingClientRect();
+        const cx = e.touches ? e.touches[0].clientX : e.clientX;
+        const cy = e.touches ? e.touches[0].clientY : e.clientY;
+        return {
+            x: Math.max(0, Math.min(canvas.width,  Math.round(cx - r.left))),
+            y: Math.max(0, Math.min(canvas.height, Math.round(cy - r.top))),
+        };
+    }
+
+    canvas.addEventListener('mousedown',  startDrag);
+    canvas.addEventListener('touchstart', startDrag, {passive: true});
+
+    function startDrag(e) {
+        const p = canvasPos(e);
+        startX  = p.x; startY = p.y;
+        sel     = {x: p.x, y: p.y, w: 0, h: 0};
+        dragging = true;
+        confirmBtn.disabled = true;
+        sizeHint.textContent = '';
+    }
+
+    window.addEventListener('mousemove',  moveDrag);
+    window.addEventListener('touchmove',  moveDrag, {passive: true});
+
+    function moveDrag(e) {
+        if (!dragging) return;
+        const p = canvasPos(e);
+        sel = {
+            x: Math.min(startX, p.x),
+            y: Math.min(startY, p.y),
+            w: Math.abs(p.x - startX),
+            h: Math.abs(p.y - startY),
+        };
+        drawCanvas();
+    }
+
+    window.addEventListener('mouseup',  endDrag);
+    window.addEventListener('touchend', endDrag);
+
+    function endDrag() { dragging = false; }
+
+    window.confirmCrop = async function() {
+        if (!sel || sel.w < 1 || sel.h < 1) return;
+        confirmBtn.disabled = true;
+        confirmBtn.textContent = 'Wird gespeichert…';
+
+        const payload = {
+            x: Math.round(sel.x * scaleX),
+            y: Math.round(sel.y * scaleY),
+            w: Math.round(sel.w * scaleX),
+            h: Math.round(sel.h * scaleY),
+        };
+
+        try {
+            const res = await fetch('/belege/' + BELEG_ID + '/crop', {
+                method: 'POST',
+                headers: {'Content-Type': 'application/json'},
+                body: JSON.stringify(payload),
+            });
+            const data = await res.json();
+            if (!res.ok) throw new Error(data.error || 'Unbekannter Fehler');
+            location.reload();
+        } catch (err) {
+            alert('Fehler beim Zuschneiden: ' + err.message);
+            confirmBtn.disabled  = false;
+            confirmBtn.textContent = 'Zuschnitt übernehmen';
+        }
+    };
+
+    // ESC schließt Modal
+    document.addEventListener('keydown', function(e) {
+        if (e.key === 'Escape' && overlay.style.display !== 'none') closeCropModal();
+    });
+
+    // Klick auf Overlay-Hintergrund schließt
+    overlay.addEventListener('click', function(e) {
+        if (e.target === overlay) closeCropModal();
+    });
+}());
+</script>
+<?php endif; ?>
+
 <?php if (!$beleg['locked']): ?>
 <script>
 document.addEventListener('DOMContentLoaded', function() {