Accelerometer Test
See live X, Y and Z motion readings from your phone, in m/s² and g, with a bubble level and a 10 second chart. Values come from DeviceMotionEvent in the browser, not a lab meter. At rest, gravity reads about 1 g on one axis.
- 1. Lay it flatZ: not yet
Screen up on a table. Z should read about ±9.8 m/s².
- 2. Stand it on its long edgeX: not yet
Rest it on a long side, screen facing sideways. X should read about ±9.8 m/s².
- 3. Stand it uprightY: not yet
Portrait, resting on the bottom edge. Y should read about ±9.8 m/s².
Hold step 1 flat for half a second to compare the browser reading with 1 g. This is not a lab calibration.
Numbers use accelerationIncludingGravity, in m/s². Gravity is included, so a rest reading near 1 g on one axis is normal. The separate acceleration field, with gravity removed, is often null, and this page does not replace that null with zero. Browsers pass the sensor through at a capped rate, usually 60 Hz, even when the chip runs faster, and some report the signs flipped. The pose check uses absolute values, so either sign counts. Readings stop while the tab is in the background.
How to read your accelerometer
What the accelerometer does
The accelerometer measures force along three axes. X runs across the screen, Y runs from the bottom edge to the top, and Z points out of the glass. This page reads accelerationIncludingGravity, so at rest the axis pointing down reads about 9.81 m/s². That is 1 g here, because the page divides by 9.80665. The other two axes sit near zero. A rest reading of 1 g is not a fault. Your phone uses this to decide when to auto-rotate, to count steps from the rhythm of your walk, and to steer tilt-controlled games. The rotation rate comes from a separate chip, which you can check with the gyroscope test.
Signs of a failing sensor
Auto-rotate that never flips (with rotation lock off), a game that drifts while you hold the phone still, or a step count that stays at zero can come from this sensor, but also from software. On this page, compare the three poses. A line that stays near zero in every pose, or a value that never changes, is a reason to retry, not a repair verdict from one sample. Jitter above about 0.5 m/s² while the phone lies on a table can mean a noisy reading. Flat on a level desk, magnitude often lands within about 0.3 m/s² of 9.81. This page does not mark an axis as dead on its own.
Fixes worth trying
Restart the phone first: a crashed sensor service is far more common than a broken chip. Some Android phones have a calibration option, often under Settings, Display, or in a hidden service menu (Samsung uses *#0*# on many models). Lay the phone on a level surface before you run it, then update the system software. If one axis still reads zero in every pose after that, a repair shop can test the chip. This browser page cannot confirm a hardware fault by itself.
The case magnet myth
Magnetic cases and car mounts get blamed for broken auto-rotate, but magnets affect the compass (magnetometer), not the accelerometer, which measures force, not magnetic fields. If the compass app points the wrong way near a mount, that is the magnet. If rotation fails, look elsewhere.
Browser permissions on iPhone and Android
iPhone and iPad (iOS 13 and later) only share motion data after you tap Start and approve the prompt, and only over HTTPS. The listener is not attached until that tap grants permission. Android Chrome allows it by default, but you can block it per site under Site settings, Motion sensors. An insecure page or a denied prompt shows a message instead of zeros. If nothing arrives on a phone, check that setting and battery saver modes.
Related tools
Check rotation sensing with the gyroscope test, the haptic motor with the vibration test, and the screen with the touch screen test and multi-touch test.
Frequently asked questions
Why does a phone at rest read about 1 g?
The page shows accelerationIncludingGravity from DeviceMotionEvent. That vector includes gravity. Sitting still, the axis that points down reads about 9.81 m/s², which this page treats as 1 g by dividing by 9.80665. The other two axes sit near zero. That pattern is gravity, not a fault. The gravity-free acceleration field is often null, so this page does not fill it in with zeros.
Why do I get no readings on a laptop?
Most desktops and laptops have no motion sensor. The browser then sends no DeviceMotionEvent values, or it sends null axes. This page shows a message and dashes, not a row of zeros. Open the same address on a phone and tap Start sensor test.
Why does iPhone ask for permission?
On iOS 13 and later, Safari shares motion data only after a tap. Start sensor test calls DeviceMotionEvent.requestPermission() from that tap. The listener starts only after you allow it. If you deny it, the page says motion access was blocked and does not show zeros. If you already denied it, close the tab, open the page again and tap Allow, or clear data for this site in Safari settings.
Is this a calibrated lab meter?
No. The numbers are the browser sensor values. X, Y and Z are meters per second squared. The g figure is that reading divided by 9.80665. If a value is not a finite number, or tilt would require dividing by a zero magnitude, the page shows a dash. Phone sensors differ from one unit to another, and the browser may cap the rate near 60 Hz.
Can this test prove the accelerometer is broken?
No. One sample, or one short session, cannot prove a hardware fault. Each pose is marked only after that axis stays near 1 g for half a second while the phone is held still. An axis that stays near zero in every pose is a reason to retry after a restart, not a repair verdict. A tilted table, a denied permission, a missing sensor, or a browser that sends nothing can look similar.
What if motion data never arrives on a phone?
The page needs a secure https connection. On an insecure page it says so and does not start the listener. If the connection is secure and nothing arrives within 3 seconds, check the site setting for motion sensors (Android Chrome lists it under Site settings) and ease off battery saving. A denied iOS prompt has its own message. None of these cases are shown as 0 m/s².