diff --git a/src/components/ComparePanel.tsx b/src/components/ComparePanel.tsx
new file mode 100644
index 0000000..6ac1e20
--- /dev/null
+++ b/src/components/ComparePanel.tsx
@@ -0,0 +1,126 @@
+import { useRef } from 'react';
+import { ImagePlus, X, ZoomIn, ZoomOut, RotateCcw } from 'lucide-react';
+import { Button } from '@/components/ui/button';
+import { useModelStore } from '@/stores/useModelStore';
+import { useState } from 'react';
+
+export function ComparePanel() {
+  const { compareImage, setCompareImage } = useModelStore();
+  const fileRef = useRef<HTMLInputElement>(null);
+  const [zoom, setZoom] = useState(1);
+
+  const handleFile = (e: React.ChangeEvent<HTMLInputElement>) => {
+    const file = e.target.files?.[0];
+    if (!file) return;
+    const url = URL.createObjectURL(file);
+    setCompareImage(url);
+    setZoom(1);
+  };
+
+  if (!compareImage) {
+    return (
+      <div className="flex h-full flex-col items-center justify-center gap-4 bg-muted/30 p-6">
+        <div className="rounded-xl border-2 border-dashed border-muted-foreground/30 p-8 text-center">
+          <ImagePlus className="mx-auto mb-3 h-10 w-10 text-muted-foreground/50" />
+          <p className="mb-1 font-mono text-sm font-semibold text-foreground">
+            Foto Real da Peça
+          </p>
+          <p className="mb-4 font-mono text-xs text-muted-foreground">
+            Carregue uma foto para comparar com o modelo 3D
+          </p>
+          <Button size="sm" className="gap-2" onClick={() => fileRef.current?.click()}>
+            <ImagePlus className="h-3.5 w-3.5" />
+            Selecionar Foto
+          </Button>
+        </div>
+        <input
+          ref={fileRef}
+          type="file"
+          accept="image/*"
+          className="hidden"
+          onChange={handleFile}
+        />
+      </div>
+    );
+  }
+
+  return (
+    <div className="relative flex h-full flex-col bg-muted/20">
+      {/* Toolbar */}
+      <div className="flex items-center justify-between border-b bg-card/90 px-3 py-2 backdrop-blur-sm">
+        <span className="font-mono text-xs font-semibold text-muted-foreground uppercase tracking-widest">
+          Foto Real
+        </span>
+        <div className="flex items-center gap-1">
+          <Button
+            variant="ghost"
+            size="icon"
+            className="h-7 w-7"
+            onClick={() => setZoom((z) => Math.max(0.25, z - 0.25))}
+            title="Zoom out"
+          >
+            <ZoomOut className="h-3.5 w-3.5" />
+          </Button>
+          <span className="font-mono text-xs text-muted-foreground w-10 text-center">
+            {Math.round(zoom * 100)}%
+          </span>
+          <Button
+            variant="ghost"
+            size="icon"
+            className="h-7 w-7"
+            onClick={() => setZoom((z) => Math.min(4, z + 0.25))}
+            title="Zoom in"
+          >
+            <ZoomIn className="h-3.5 w-3.5" />
+          </Button>
+          <Button
+            variant="ghost"
+            size="icon"
+            className="h-7 w-7"
+            onClick={() => setZoom(1)}
+            title="Reset zoom"
+          >
+            <RotateCcw className="h-3.5 w-3.5" />
+          </Button>
+          <Button
+            variant="ghost"
+            size="icon"
+            className="h-7 w-7"
+            onClick={() => fileRef.current?.click()}
+            title="Trocar foto"
+          >
+            <ImagePlus className="h-3.5 w-3.5" />
+          </Button>
+          <Button
+            variant="ghost"
+            size="icon"
+            className="h-7 w-7"
+            onClick={() => { setCompareImage(null); setZoom(1); }}
+            title="Remover foto"
+          >
+            <X className="h-3.5 w-3.5 text-destructive" />
+          </Button>
+        </div>
+      </div>
+
+      {/* Image */}
+      <div className="flex-1 overflow-auto flex items-center justify-center">
+        <img
+          src={compareImage}
+          alt="Foto real da peça"
+          className="max-w-none transition-transform duration-150"
+          style={{ transform: `scale(${zoom})` }}
+          draggable={false}
+        />
+      </div>
+
+      <input
+        ref={fileRef}
+        type="file"
+        accept="image/*"
+        className="hidden"
+        onChange={handleFile}
+      />
+    </div>
+  );
+}
diff --git a/src/pages/Viewer.tsx b/src/pages/Viewer.tsx
index bfaa738..d095d00 100644
--- a/src/pages/Viewer.tsx
+++ b/src/pages/Viewer.tsx
@@ -1,5 +1,5 @@
 import { useNavigate } from 'react-router-dom';
-import { ArrowLeft, Glasses, Box, Ruler, FileText } from 'lucide-react';
+import { ArrowLeft, Glasses, Box, Ruler, FileText, Columns2 } from 'lucide-react';
 import { Button } from '@/components/ui/button';
 import { useModelStore } from '@/stores/useModelStore';
 import { ModelViewerCanvas } from '@/components/three/ModelViewer';
@@ -8,6 +8,7 @@ import { InspectionChecklist } from '@/components/InspectionChecklist';
 import { FineTuningControls } from '@/components/FineTuningControls';
 import { MeasurementsList } from '@/components/MeasurementsList';
 import { ScreenshotGallery } from '@/components/ScreenshotGallery';
+import { ComparePanel } from '@/components/ComparePanel';
 import { useEffect } from 'react';
 import { toast } from 'sonner';
 import { ScrollArea } from '@/components/ui/scroll-area';
@@ -15,7 +16,7 @@ import { Separator } from '@/components/ui/separator';
 
 const Viewer = () => {
   const navigate = useNavigate();
-  const { model, xrSupported } = useModelStore();
+  const { model, xrSupported, compareMode, setCompareMode } = useModelStore();
 
   useEffect(() => {
     if (!model) {
@@ -49,23 +50,41 @@ const Viewer = () => {
           </div>
         </div>
 
-        <Button
-          className="gap-2 glow-primary"
-          disabled={!xrSupported}
-          onClick={handleEnterXR}
-        >
-          <Glasses className="h-4 w-4" />
-          Entrar em Modo XR
-        </Button>
+        <div className="flex items-center gap-2">
+          <Button
+            variant={compareMode ? 'default' : 'outline'}
+            size="sm"
+            className="gap-2"
+            onClick={() => setCompareMode(!compareMode)}
+          >
+            <Columns2 className="h-4 w-4" />
+            Comparar
+          </Button>
+          <Button
+            className="gap-2 glow-primary"
+            disabled={!xrSupported}
+            onClick={handleEnterXR}
+          >
+            <Glasses className="h-4 w-4" />
+            Entrar em Modo XR
+          </Button>
+        </div>
       </header>
 
       <div className="flex flex-1 overflow-hidden">
         {/* 3D Canvas with floating controls */}
-        <div className="relative flex-1">
+        <div className={`relative ${compareMode ? 'w-1/2' : 'flex-1'}`}>
           <ModelViewerCanvas url={model.url} />
           <ViewerControls />
         </div>
 
+        {/* Compare panel */}
+        {compareMode && (
+          <div className="w-1/2 border-l">
+            <ComparePanel />
+          </div>
+        )}
+
         {/* Side panel */}
         <aside className="w-80 shrink-0 border-l bg-card">
           <ScrollArea className="h-full">
diff --git a/src/stores/useModelStore.ts b/src/stores/useModelStore.ts
index 2286eee..9be44cd 100644
--- a/src/stores/useModelStore.ts
+++ b/src/stores/useModelStore.ts
@@ -91,6 +91,11 @@ interface ModelStore {
   clearMeasurements: () => void;
   removeMeasurement: (id: string) => void;
 
+  compareMode: boolean;
+  setCompareMode: (on: boolean) => void;
+  compareImage: string | null;
+  setCompareImage: (url: string | null) => void;
+
   screenshots: string[];
   addScreenshot: (dataUrl: string) => void;
   removeScreenshot: (index: number) => void;
@@ -176,6 +181,11 @@ export const useModelStore = create<ModelStore>((set) => ({
     measurements: state.measurements.filter(m => m.id !== id),
   })),
 
+  compareMode: false,
+  setCompareMode: (compareMode) => set({ compareMode }),
+  compareImage: null,
+  setCompareImage: (compareImage) => set({ compareImage }),
+
   screenshots: [],
   addScreenshot: (dataUrl) => set((state) => ({ screenshots: [...state.screenshots, dataUrl] })),
   removeScreenshot: (index) => set((state) => ({