How to use the protractor camera
- Tap Start camera and allow camera access. The rear camera opens by default on phones.
- Frame the angle. Point the camera straight at the corner you want to measure and keep it near the middle of the screen.
- Tap Freeze to stop the picture. Now you can put the phone down or hold it comfortably.
- Drag the protractor so its center sits on the corner, then drag handles A and B along the two lines. The angle updates live.
- Download a snapshot to save the frozen image with the protractor and angle drawn on it.
Camera or photo: which should I use?
The camera is fastest for a quick check, like the angle of a chair leg, a plant stem or a ramp you are standing next to. For careful work, take a normal photo (your camera app has better focus and zoom) and use Measure Angle from Photo, which adds a magnifier, multiple measurements and full-resolution export. To measure the tilt of a surface you can touch, the phone's built-in sensor in the Angle Finder is the most accurate option.
Getting accurate results
- Avoid perspective. Photographing an angle from the side distorts it. Line the camera up square to the surface.
- Mind the lens. Wide lenses curve lines near the edges. Keep the subject centered and step back rather than moving closer.
- Freeze first. Small hand movements shift the image; freezing gives you a stable picture to line the arms up on.
Frequently asked questions
Is the camera video recorded or uploaded?
No. The camera feed is shown only on your screen. Nothing is recorded, stored or sent anywhere. Snapshots are saved only when you tap Download, straight to your own device.
Why does the camera not start?
Your browser needs your permission to use the camera, and the page must be loaded over https (it is). If you tapped "Block", allow the camera for this site in your browser settings and reload. On iPhone use Safari or Chrome with iOS 14.3 or newer.
How do I get an accurate reading with the camera?
Hold the phone so the camera looks straight at the angle, not from the side, and keep the angle in the middle of the picture. Then tap Freeze so the image stops moving, and drag the arms precisely onto the lines.
Can I use the front (selfie) camera?
Yes. If your device has more than one camera, tap "Switch camera". The front camera view is mirrored like a mirror, but angle sizes are not affected.