Image mode
Measure Angle From Image – Free Photo Angle Finder
Measure angle from image or photo — upload a PNG, JPG/JPEG or WebP and overlay the protractor. Zoom, pan and rotate the photo or diagram, then drag the protractor center to the vertex. The tool measures the 2D angle in the picture locally in your browser — your photo is never uploaded.
Free•No sign-up•Works in browser•Image stays local
Updated Online Protractor
Keyboard: Tab handles, arrows nudge 1px center / 1° ray (Shift 10px / 5°), R reset, G grid, L lock baseline, Z undo, Shift+Z redo, +/- zoom. Endpoint magnifier shows while dragging. Drag center, baseline ray, second ray. Snap preview before commit. Image stays local — never uploaded. Press Esc to exit fullscreen.
Camera stays local — capture is processed in your browser
How image measurement works: Use Use image or drag & drop, or paste with Ctrl+V. The file is read via FileReader/Object URL and never leaves your device. Fit, zoom (+/− buttons), pan (drag image), rotate (slider or 90° buttons), and reset view. Move the protractor center separately from the image. Adjust overlay opacity or high-contrast for legibility.
Accuracy: what changes the apparent angle
- Perspective distortion can change the apparent angle — a rectangle photographed at an angle looks like a trapezoid; the tool measures the 2D projection you see, not the physical object.
- Wide-angle camera distortion can bend straight lines near the edges; center the subject and avoid extreme wide-angle.
- 2D vs 3D: the tool measures the apparent 2D angle in the image pixels; it does not prove the real-world 3D angle without controlled setup.
- Use the crosshair, grid, and magnifier to place the vertex precisely; enable high-contrast for pale photos.
Processed in your browser; the image is not uploaded. We do not store images in localStorage; Object URLs are revoked when replaced.
Privacy & errors
- Privacy: Images are read locally via Blob URLs, never uploaded. Clearing the image revokes the URL.
- Unsupported file: Only PNG, JPG/JPEG, WebP are accepted.
- Too large: Files over 12 MB are rejected with a message.
- Corrupted: If the image cannot decode, you’ll see “Corrupted image or unsupported encoding.”
- Clipboard: If your browser blocks paste, use drag & drop or the file picker.
- No image: The “Use image” button and drop zone show until you load one.