How to Measure an Angle With Your Phone (3 Ways)

Short answer: open a protractor app, put the vertex on the corner of the angle, and drag one arm along each side. For real objects, either line the arms up through the camera or take a photo first and measure on the photo, which is easier to zoom.

1. On the screen, like a paper protractor

For a drawing, a printout or a small part, lay it next to the phone or hold the phone over it. Drag the vertex to the corner, then drag each arm along a side. Read the big number at the top; the other angle (180° minus it) is shown underneath.

2. Through the camera

Switch the background to Camera. Hold the phone parallel to the surface, about an arm's length away, and line the two arms up with the edges you want. Lock the reading with Hold before you move the phone.

3. On a photo

Take a straight-on photo, then open it as the background. Pinch with two fingers to zoom in on the corner. Because the photo does not shake, this is usually the most precise way to measure something large, like a roof line or a staircase.

Getting a clean reading

Stand square to the object; slanted views distort angles.
Zoom in so each arm covers a long, straight part of the edge.
Measure twice from opposite sides and average if it matters.

Doing it with Anglora

Anglora has all three modes on one screen: Plain, Camera and Photo. Drag either arm or tap where you want it, switch between 180° and 360°, and save the result with a name.

Frequently asked questions

How accurate is a phone protractor?

About one degree when the arms are lined up carefully. Zoom in on a photo or move the phone closer to the edge for better results.

Why does the camera angle look wrong?

The camera sees the object in perspective. Hold the phone parallel to the surface you are measuring, not at a slant.

Can I measure an angle bigger than 180°?

Yes. Switch the protractor to 360° and the reading goes all the way around.

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