How it works
Shows live what the phone or tablet's motion sensors measure. The accelerometer reports the acceleration in the three axes in meters per second squared and stores the maximum reached, useful for checking that it responds to a sharp blow or a shake.
The gyroscope reports spin speed in degrees per second about each axis, and orientation data—alpha, beta, and gamma—feeds a bubble level that turns green when the device is perfectly horizontal. If there is a magnetometer, the compass indicates the heading with respect to north.
It is completed with the ambient light sensor, when exposed by the browser, and with a vibration motor test with three different patterns. All readings are processed on the device and none are sent to a server.
Examples
Device supported and still9,8 m/s²It is Earth's gravity. If the device reports the acceleration without gravity, at rest the value is close to zero.beta: 0° · gamma: 0°perfectly horizontal surfacebeta measures forward and backward tilt; gamma, lateral inclination. With both at zero the bubble is centered.alpha: 90°heading 270° (west)The compass heading is calculated by subtracting alpha from 360, because alpha grows counterclockwise.Use cases
- Check if the accelerometer or gyroscope still works after a fall.
- Find out why the screen does not rotate on its own: it is almost always the sensor, not the system.
- Use the phone as a level to hang a picture or align a shelf.
- Check the compass before going for a walk or using a navigation app.
- See what values the sensors return while developing a web application that reacts to motion.
Frequently asked questions
Why don't I see any readings?
Desktop computers and most notebooks do not have an accelerometer or gyroscope, so the browser does not deliver anything even if the events exist. I opened the page from a phone or tablet, and moved the device: some sensors only emit when there is movement.
Why does the iPhone ask for permission?
Since iOS 13, Safari requires explicit user authorization to deliver movement and orientation data, because those readings were used to identify devices and even to deduce what is written on the screen. Permission is requested when reading is started and must be granted from the system prompt.
What is the difference between acceleration with and without gravity?
The sensor always measures gravity plus movement. Devices with a gyroscope can separate both things and provide linear acceleration on the one hand and total acceleration on the other. If the computer cannot separate them, at rest you will see about 9.8 m/s² on the axis pointing downward.
Why does the compass point wrong?
The magnetometer is altered by any nearby magnetic field: cases with magnets, speakers, wireless chargers or a metal structure. It also needs calibration, which on most phones is done by moving the device drawing a figure eight in the air. It also marks the magnetic north, which does not coincide exactly with the geographic north.
Why isn't vibration working on my phone?
Safari on iOS does not implement the vibration API, so there is no way to activate it from the browser on an iPhone. On Android it works in Chrome and derivatives, as long as the device is not in silent mode with vibration disabled and that you have interacted with the page before.