How to use the accelerometer test
- Starting: The test starts by itself. On iPhone and iPad, tap Allow motion access and accept the prompt first.
- Total force (g): The combined force on the device. Lying still it should read about 1.00 g, which is gravity; shaking or dropping it changes the number.
- X, Y and Z: The force along each axis in metres per second squared, including gravity. X runs left to right across the screen, Y runs up and down the screen, and Z goes through the screen. Lay the phone flat and Z shows about 9.8 m/s² while X and Y stay near 0.
- Bubble level: The bubble floats to the high side, like a real spirit level. The inner ring means within about a degree; when the device is level, the rim turns green and Tilt reads "Level".
- Tilt: How far the device is tilted front to back and side to side, in degrees.
- Peak force: The highest total force since the page opened.
- Movement (no gravity): Acceleration with gravity taken out, where the device reports it. It reads near 0 when the device is still.
- Readings per second: How often the browser delivers readings, usually 60 Hz or more on phones.
What healthy readings look like
- Lying flat: Total force about 1.00 g (between 0.98 and 1.02 is normal), with Z near 9.8 m/s² and X and Y near 0.
- Standing upright: Y takes over at about 9.8 m/s² while Z drops toward 0.
- Moving: All three axes respond smoothly, and the readings settle back once you stop.
- Faulty accelerometer: Total force far from 1 g while still, an axis stuck at one value, or a level that's clearly off on a surface you know is flat.
Common Issues & Fixes
It says no accelerometer readings came in
- Device: Most laptops and desktops don't have an accelerometer. Try a phone or tablet.
- Permission: On iPhone and iPad, motion access has to be allowed. If you declined it, close the tab and open the test again.
- Browser: Use a current version of Chrome, Safari, Edge, Firefox or Samsung Internet. Some privacy-focused browsers block motion sensors.
The bubble level isn't accurate
- Case: A thick or uneven case tilts the phone. Take it off for accurate readings.
- Calibrate: Some phones have a sensor calibration option in their settings or diagnostic menu. Check against a surface you know is level.
- Camera bump: Lying on its back, a phone with a camera bump isn't flat. Measure with the screen facing down or the phone on its edge instead.
The screen doesn't rotate even though the readings look fine
- Rotation lock: Check that auto-rotate or rotation lock isn't turned on in your quick settings.
- App: Some apps only allow one orientation.
Use this accelerometer test for a quick health check of your device's motion sensor, or as a handy level. Its sibling, the gyroscope test, checks the sensor that measures rotation.
Frequently asked questions
Why does it read 1 g when my phone isn't moving?
Accelerometers feel gravity as a constant upward force of about 9.8 m/s², which is 1 g. That's how phones know which way is down, and it's why the readings include gravity.
How accurate is the bubble level?
Usually within a degree or so, which is fine for hanging pictures or checking shelves. For construction work, use a real spirit level.
Is any of my data sent anywhere?
No. The readings are shown in your browser and never sent to our server.