Bubble Level

Angle finder · between two faces

0.0

Waiting for sensor

0.0° From level 0.0° Reference 90.0° To square
Tap Start to read the sensor

Place the phone on the first surface and tap Set reference. Then move it to the second surface.

How do you measure the angle between two surfaces?

Place the phone flat on the first surface and tap Set reference. The dashed arm stays in that position and the reading returns to zero.

Move the phone to the second surface, keeping it the same way round. The number now shows the angle between the two surfaces.

A level can only measure against gravity. That does not help when both surfaces are already tilted.

Choosing your own zero position is what a sliding bevel does. That is why this page has Set reference where the other tools have Calibrate.

How do you work out a mitre cut?

Divide the reading by two. Each of the two pieces takes half of the angle, so a 92° corner needs two cuts of 46°, not 45°.

Note that the reading is the angle you turned through, not the angle of the corner itself.

An internal corner is 180° minus the reading. An external corner is 180° plus the reading.

If the phone has to go somewhere you cannot see the screen, tap Hold first. The number stays fixed until you tap it again.

Frequently asked questions

How do I measure the angle of a corner?

Place the phone on the first surface and tap Set reference. Then place it on the second surface the same way round. The reading is the angle you turned through. An internal corner is 180° minus that number, and an external corner is 180° plus it.

How do I work out a mitre cut?

Divide the corner angle by two. A 90° corner needs two cuts of 45°, and a 92° corner needs two cuts of 46°. Check which scale your saw uses before you cut an expensive length.

What does the Hold button do?

It fixes the reading so that it stops following the phone. Use it when the phone has to go somewhere you cannot see the screen. Tap it again to continue.

What does the "to square" figure show?

It shows how far the reading is from a right angle, so you do not have to work it out. A room that is 1.5° out over 3 m has walls almost 8 cm apart at the far end.

How is this different from the inclinometer?

The inclinometer measures from level and reports a slope. This page measures from a surface you choose and reports the angle between two surfaces.

Does the reference stay after I reload the page?

No. A reference surface only applies to the job in front of you. The calibration offset does stay, because it belongs to the phone rather than to the task.