Phone sensor / Level
Bubble Level Online
Turn your phone into a spirit level: a bubble and an angle in degrees, lying flat on a surface or standing on its edge against a shelf or frame.
Bubble Level Online: The phone's accelerometer measures which way gravity pulls, and the page turns that into a tilt angle: the bubble floats to the higher side, as in a spirit level. Lying flat it shows the tilt in both directions; standing on an edge it shows the angle of that edge. Readings are smoothed so the bubble settles, and turn green within 0.3 degrees of level. Runs 100% locally in your browser with zero server file uploads.
- Category
- Everyday tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
Calibrating with the reversal method
Builders check a level by turning it round: lay the phone on a flat surface and note the angle, turn it 180 degrees on the same spot, and note it again. If the two readings differ, the true tilt of the surface is their average, and half the difference is the phone's own error. Press Set zero here with the phone on a surface the two readings show is level.
To measure a length as well as a level, use the online ruler.
Degrees and slopes
A slope of 1 in 100, the usual fall for a patio or a gutter, is about 0.57 degrees; 1 in 50 is about 1.15 degrees; 1 in 12, the steepest wheelchair ramp most building codes allow, is about 4.8 degrees.
How to use it
- Press Start the level; on iPhone, tap Allow when asked for motion access.
- Lay the phone on the surface, or stand it on its long edge against a shelf or picture frame.
- Read the angle; press Set zero here on a surface you know is level to calibrate, and Hold the reading to keep it.
Privacy & limitations
The motion readings stay in your browser; nothing is recorded or sent.
Related tools
Frequently asked questions
How accurate is a phone level?
Typically within a few tenths of a degree once calibrated, which is good for shelves and pictures. A phone case with a bump or a camera that sticks out can tilt it, so calibrate on a surface you trust, or measure, turn the phone round, and take the average.
Why does my iPhone ask for motion access?
Safari asks before a website can read the motion sensors. If you tapped Don't Allow, close the tab and open the page again to be asked once more.
Why does nothing happen on my laptop?
Most computers have no tilt sensor. Open the page on a phone or tablet.
Free tool · runs in your browser · no account required