Drop an image to start measuring

Measure distance and area on an image

Measure turns any picture into a measuring surface. Give it one known length and it converts image pixels into real-world units, so you can read distances, areas and perimeters straight off a photo, screenshot, map, floor plan or site plan — in the browser, with nothing to install.

How it works

1. Set the scale. Drag a line across something whose real size you already know — a doorway, a car, a scale bar, a road width — and type that length in. This one reference is what every later measurement is derived from.
2. Draw your measurements. Lines give distances, polylines give running totals, and polygons give area together with perimeter, with each edge labelled. Text notes and callouts can be pinned to any shape.
3. Read and export. Values update live in the side panel. Export an annotated PNG, JPEG or WebP at up to 3×, optionally with a legend listing every measurement, or save a project file that reopens with the image and all your work intact.

Frequently asked questions

Are my images uploaded anywhere?

No. Images are read with FileReader and decoded in the page. The file contains no fetch, XMLHttpRequest, WebSocket or sendBeacon call and no third-party script, so there is nothing to send data with. It works with the network disconnected entirely.

How accurate is it?

Accuracy is bounded by your calibration, so use the longest reference available and zoom in when placing its ends. A 1-pixel error on a 100-pixel reference is a 1% error on every measurement; on a 1000-pixel reference it is 0.1%.

Can I measure areas on a map or satellite image?

Yes — calibrate against the map's scale bar, or against a feature of known length. Overhead imagery is the ideal case because it has almost no perspective distortion.

Why do my measurements look wrong on an angled photo?

Measurements are only valid in the plane the reference lies in. A photo taken at an angle has perspective, so objects further away measure too small, and areas on the ground are not comparable to areas on a wall. For dependable numbers use straight-on or overhead imagery such as orthophotos, plans, scans or screenshots.

Which units are supported?

Metric — millimetres, centimetres, metres and kilometres, with areas promoting m² → hectares → km². US customary — inches, feet, yards and miles, with areas promoting ft² → acres → mi². US lengths display as feet and inches with reduced fractions, and the input field accepts the same notation, so 16' 6" parses. Changing the display unit never recalculates geometry.

Does it cost anything, or need an account?

No. It is free, has no account, no sign-up and no usage limits.