Accelerometer Test
Check your phone or tablet’s accelerometer in the browser. Tap Start and move the device — X, Y and Z report live acceleration in m/s², the meter shows combined g-force, and every shake is counted.
Tap Start, then move the phone — each axis reads live in m/s².
Open this page on the phone or tablet you want to test — computers rarely have motion sensors.
A phone at rest reads about 1G — that is gravity. Only free fall reads zero.
Move left-right, then up-down, then toward you, so each axis responds on its own.
Quick shakes spike the g-force past 1G and bump the counter — the signal behind shake-to-undo.
The accelerometer drives auto-rotate, step counting, shake gestures, and every motion-controlled game. When it drifts or dies, those features fail confusingly: the screen stops rotating, a fitness app miscounts steps, a racing game pulls to one side. This test reads the sensor directly, so you can tell in seconds whether the hardware reports motion at all and whether each axis responds — worth thirty seconds before buying a used phone, after a drop or a repair, or when a motion app misbehaves and you want to know if the app or the sensor is at fault. Pair it with the Touch Screen Test to check the screen at the same time.
The test listens to the browser’s DeviceMotion API, the same motion stream web games receive. Readings arrive many times per second in metres per second squared (m/s²), where 9.81 m/s² equals 1G — one Earth gravity. The axis readouts include gravity, which is what makes them easy to interpret: a phone flat on a table shows about +9.8 on Z and near zero on X and Y, and tilting it moves that 9.8 between the axes. The shake counter uses the gravity-free stream, so only genuine jolts count. On iPhones and iPads, iOS asks for motion-sensor permission when you tap Start — nothing is read until you allow it. Nothing is uploaded; the numbers never leave the page.
How do you read the X, Y and Z values?
| Axis | Direction | What you should see |
|---|---|---|
| X | Across the screen — left and right | Slide the phone sideways on a table: X swings negative and positive while Y and Z barely move |
| Y | Along the screen — bottom to top | Slide it away and back, or stand it upright: Y responds while X and Z stay quiet |
| Z | Through the screen — front to back | Face up at rest, Z reads about +9.8 m/s² (gravity); face down it settles near −9.8 |
Why does it read 1G when the phone is perfectly still?
An accelerometer measures force, not movement. A phone resting on a table is pushed up by the table with exactly one gravity of force, so a healthy sensor reads 1G at rest — it would only read 0G in free fall. It is also why the numbers swing the opposite way when you stop moving: halting the phone is a deceleration, and the sensor reports it as acceleration in reverse before settling back to 1G. Both behaviours mean the sensor is working, not glitching.
Accelerometer vs. gyroscope
The accelerometer measures linear force — pushes, pulls, gravity, shakes. The gyroscope measures rotation rate, how fast the device turns around each axis. Rotating the phone slowly barely registers here beyond gravity shifting between axes, and that is expected: rotation is the gyroscope’s job. Most motion features combine both sensors, so if apps still misbehave after every axis passes, the gyroscope is the next suspect — check it with the Gyroscope Test.
No readings? Troubleshooting
| Problem | Likely cause | Fix |
|---|---|---|
| Every value stays blank on a computer | Desktops and most laptops have no accelerometer | Open this page on a phone or tablet |
| No permission prompt and no data on an iPhone | Motion access was denied for this site earlier | In Safari: the “aA” menu → Website Settings → allow Motion & Orientation Access, then reload |
| The prompt never appears in another browser | Motion sensors need a secure page, and some in-app views block them | Open the page over HTTPS in a full browser, not inside an in-app view |
| Values are frozen or update in bursts | Battery saver or an OS sensor glitch is throttling the stream | Turn off power saving, restart the device, then retest |
| One axis never moves | The sensor or its calibration has failed on that axis | Restart and retest; if it stays flat, the sensor is faulty — worth knowing before you buy or file a repair claim |