AR Tape Measure
Free AR tape measure online. Measure real-world distance with your phone camera — WebXR AR mode runs on Android Chrome with ARCore, reference-photo mode works on every browser including iPhone Safari. No app to install, no signup.
How reference-photo measurement works
- Take or upload a photo with a credit card, dollar bill, or coin in frame on the same surface as the thing you want to measure.
- Pick the reference object below (or set a custom length in millimetres).
- Click two points along the reference's known edge.
- Click two points to measure between. The tool converts pixel distance to real distance.
Drop a photo here or click to upload
JPG or PNG, kept private in your browser
An AR tape measure (also called an AR measure tape) is a browser tool that estimates real-world distance using your phone camera. On Android Chrome with ARCore it uses the WebXR Hit Test API to drop two virtual anchors on a real surface and report the distance between them. On iPhone Safari and other browsers without WebXR, it falls back to a reference-object photo workflow — calibrate against a credit card or coin, then click two points on the photo and the pixel distance is converted to millimetres. No app to install. Last updated April 2026.
How the WebXR Hit Test mode works
The WebXR Device API exposes a special XRSession of type "immersive-ar". Inside that session, the browser asks ARCore to track your phone's position in real space and detect flat surfaces. When you tap the screen, a hit test ray is cast from the phone into the scene; the first surface it intersects becomes an anchor. Two anchors give you a 3D vector — its length is the metric distance. Three.js handles the rendering of the reticle (the green target) and the line between anchors. All processing is on-device.
How the reference-photo mode works
When you click two points along a known-length object, the tool reads the screen-pixel distance between them. Dividing the reference's millimetre length by that pixel distance gives a millimetres-per-pixel scale. When you click two more points anywhere else on the photo, multiplying their pixel distance by the scale gives the real-world distance. Accuracy depends on the camera being roughly perpendicular to the surface and the reference being on the same plane as what you are measuring.
Tips for accurate measurement
Place the reference object next to the thing you want to measure, on the same flat surface. Hold the camera directly above (top-down) for floors, tables, and counters. For walls, hold the camera perpendicular to the wall, not at an angle. Avoid wide-angle distortion at the edges of the photo — measure things near the centre when possible. For very long distances or precise jobs (carpentry, plumbing, masonry), a real tape is still better.
WebXR vs ARKit Measure app
Apple's iPhone Measure app uses ARKit, often with a LiDAR scanner on Pro models, and is generally accurate to a centimetre or two. WebXR Hit Test on Android uses ARCore and is similar in accuracy on flagship phones with depth sensors. Where this AR Measure Tape wins is universality — the same browser tool works on Android Chrome (full AR), iPhone Safari (photo mode), tablets, laptops, and even Windows PCs with a webcam — without an app store install or 100+ MB download.
Privacy
Your camera frames during a WebXR session are passed to ARCore on your phone and never leave the device. Photos uploaded for reference mode are loaded into a hidden <img> element and a canvas, both inside your browser tab. Nothing is sent to any server. Closing the tab discards everything.