Image Measurement Tool
Measure lengths and angles on a photo. Set one known distance to show real-world lengths; angles use the photo geometry and need no length scale.
- 1Load image→
- 2Set scale→
- 3Measure
Or drag an image here; you can also paste with Ctrl/Cmd + VEverything runs in your browser — the image is never uploaded to a server.
How to measure on a photo
- Choose a photo to load it. On desktop, you can also drag it onto the page or paste with Ctrl/Cmd + V.
- Click two points on a distance you already know and type its real length — this sets the scale.
- Use Length to click two points. Angle works with or without a length scale: click three points, corner first.
- Fine-tune any endpoint by dragging it, review results in the side list, and export an annotated PNG.
Frequently asked questions
Is my photo uploaded anywhere?
No. The tool runs entirely in your browser; the image never leaves your device and nothing is stored on a server.
How accurate are the measurements?
It depends on your reference length and the photo's geometry. Objects in the same plane as the reference, photographed square-on, measure best; perspective and lens distortion add error, and an error in the reference length carries proportionally into every result.
What should I use as a reference length?
Anything with a known size in the same plane as what you measure: a ruler, an A4 sheet (297 mm), a credit card (85.6 mm), or a door height.
Can I measure angles?
Yes. Angle does not need a length scale. Pick the Angle tool and click three points — the corner first, then one point on each arm. The inner angle is shown to 0.1°.
Does zooming change my measurements?
No. Points are stored in original image pixels, so zooming and panning only change the view, never the values.
What image sizes are supported?
Format support depends on what your browser can decode. Images over 4096 px on either side are reduced for the workspace, while measurements keep original pixel coordinates; PNG export can still depend on available browser memory.