| x | y | z | |
|---|---|---|---|
| With gravity (m/s²) | - | - | - |
| Without gravity (m/s²) | - | - | - |
| Rotation rate (°/s) | - | - | - |
| Angle (°) | - | - | - |
Lying still on a table, with gravity shows about 9.8 on z and without gravity shows about 0. Nothing leaves your device.
About the accelerometer test
Does your phone not turn the screen when you rotate it? Does a game steer by itself? This accelerometer test shows what the motion sensor of your phone or tablet measures, live, in the browser.
You see the acceleration on the three axes with and without gravity, the rotation rate from the gyroscope, the angles of the device, the g-force and how many readings per second arrive. A graph draws the last five seconds, and a ball rolls across the box when you tilt the device — a quick way to see that the sensor reacts in every direction.
On an iPhone or iPad, tap Allow motion sensor first. Desktop computers and most laptops have no motion sensor; the page tells you when none is found. Nothing is sent anywhere.
Features
- Acceleration with gravity — what the sensor feels, in m/s² on x, y and z
- Acceleration without gravity — only your own movement, where the device can work it out
- Rotation rate — how fast the device turns around each axis, in degrees per second
- Angles — the tilt of the device from the orientation sensor
- g-force now and highest — the total force in g, with a reset
- Live graphs — the last 5 seconds of any of the three, with a pause button
- Rolling ball — tilt the device and the ball rolls downhill
- Sample rate — how many readings per second reach the page
Reading the numbers
The axes belong to the device, not to the room:
- x runs along the short edge — positive to the right
- y runs along the long edge — positive towards the top of the screen
- z comes out of the screen — positive towards you
A sensor at rest feels gravity as a push of about 9.8 m/s² upwards (1 g). What you should see when the device is still:
| Position | With gravity | Without gravity |
|---|---|---|
| Flat on a table, screen up | z ≈ 9.8, x and y ≈ 0 | all ≈ 0 |
| Standing upright (portrait) | y ≈ 9.8 | all ≈ 0 |
| Lying on its left edge (landscape) | x ≈ 9.8 | all ≈ 0 |
| Flat, screen down | z ≈ −9.8 | all ≈ 0 |
Small changes in the last digit are normal sensor noise. g-force is the total of the three axes divided by 9.81, so a device at rest shows about 1.00 g. Some older iPhones give the opposite signs; the ball still rolls the right way, because the page checks the signs against the angles.
What the test can show
- A sensor that is stuck — the numbers do not change at all when you move the device
- An axis that is dead — one of x, y or z stays at 0 whatever you do
- A sensor that is off — lying flat and still, z is far from 9.8 or x and y are far from 0
- A gyroscope that drifts — the rotation rate does not go back to about 0 when the device lies still
- No gyroscope — the rotation rate stays "-" (some cheaper phones have none)
If the screen does not rotate but the numbers here change normally, the sensor works: check the auto-rotate setting of your phone.
Frequently asked questions
How do I test the accelerometer of my phone?
Open this page on the phone, allow the motion sensor if asked, and move the phone. The numbers and the graph should change, and the ball should roll when you tilt. Lay the phone flat: z should be close to 9.8.
Why does it say there is no motion sensor?
Desktop computers and most laptops have no accelerometer, so there is nothing to read. Open the page on a phone or tablet. Some browsers also block the sensor on pages that are not secure (https).
Why do I need to tap "Allow motion sensor"?
iPhones and iPads ask for permission before a web page can read the motion sensor. Tap the button and choose Allow. If you refused once, allow it again in the browser settings for this site and reload the page.
What is the difference between "with gravity" and "without gravity"?
With gravity is what the sensor really feels, including the pull of the earth. Without gravity takes the pull of the earth away, so it shows only your own movement — about 0 when the device lies still. Not every device or browser gives both; a missing value shows "-".
Is the gyroscope tested too?
Yes. The rotation rate comes from the gyroscope. Turn the device and the rotation numbers rise; lay it still and they go back to about 0.
Why is the sample rate only about 60 Hz?
Browsers usually pass on about 60 readings per second, even when the sensor itself can do more. For a test that is plenty.
Does anything leave my phone?
No. The sensor values are read and shown in the page only. Nothing is saved or sent anywhere.
Related tools
- Bubble Level — use the same sensor as a spirit level
- Online Compass — find north with your phone
- Speedometer — your speed from GPS
- Touch Screen Test — check every finger and find dead zones
- Gamepad Tester — test a game controller and stick drift
How to use it
- Open this page on your phone or tablet
- On an iPhone or iPad, tap Allow motion sensor and choose Allow
- Tilt the device — the ball rolls downhill and the numbers change
- Lay it flat on a table: with gravity should show z ≈ 9.8, without gravity ≈ 0
- Pick a graph — with gravity, without gravity or rotation rate — and shake or turn the device
- Press Pause to read the graph, and Reset highest to measure a new g-force
