What a moving accelerometer graph can tell you

You tilt your phone or tablet and the accelerometer graph starts moving. That change can show how the device responds to movement, but it does not automatically mean the sensor is faulty. A steady graph can be normal too, especially when the device is resting.

Use the Sensors Test to watch motion readings change as you hold the device still, tilt it, and move it gently. The patterns can help you spot an unresponsive axis, unexpected jumps, or ordinary effects of gravity.

Watch the accelerometer graph

1. Open the Sensors Test on the device whose sensor you want to check. Sensor readings must come from that device, not from another computer you use to view the page.
2. If the browser asks for permission to access motion or sensors, allow it. Keep the test page in the foreground while you check the readings.
3. Set the device on a stable, flat surface. Watch the graph for several seconds without touching the device. Note whether the lines stay mostly steady or keep changing.
4. Pick the device up and slowly tilt it forward, backward, and from side to side. Pause after each movement and watch whether the graph changes, then settles again.
5. Move the device gently in a short straight line, stop, and repeat in a different direction. Avoid shaking it hard or dropping it. Look for changes that happen in step with your movements.

If the test does not show an accelerometer graph, the browser or device may not provide that sensor to web pages. That absence alone is not evidence of a hardware fault.

What the graph can tell you

The lines change when you tilt the device

This is usually expected. An accelerometer measures acceleration, and gravity is part of what it senses. When you tilt a device that is otherwise still, gravity is distributed differently across its sensor axes, so the readings can change even though you are not moving it across the room. If the graph labels axes such as x, y, and z, each line represents a different direction relative to the device.

The graph changes during movement, then settles

A brief change as you move the device, followed by readings that become steady when you stop, is a typical response. The size and shape of the change depend on how quickly you moved, how the device is held, and how the browser presents the readings. Use the pattern to check for a response, not to measure an exact distance or judge whether your movement was perfectly smooth.

The graph moves while the device is resting

Small variations can come from slight movement of the table, the device, or your hand. Sensor noise, meaning small fluctuations in a reading, can also make a line look active. Put the device on a firm surface and leave it untouched. If the changes become much smaller, your setup was probably moving. A browser graph is not a precision instrument for measuring tiny vibrations.

One line stays flat or the readings do not change

First make sure the device is actually moving in a direction that should affect that axis. Depending on how the sensor is mounted and how the graph is displayed, a particular line may change very little during one movement. Try a slow tilt in several directions. If every line remains unchanged, check browser permission and support before suspecting the hardware.

The readings jump or look unusual

A sudden change can reflect a quick movement, a bump, or a momentary interruption in sensor updates. Repeat the same gentle movement a few times. If the graph repeatedly jumps while the device is still, or fails to respond consistently, compare it in another supported browser or on another device if available. A browser test can reveal a symptom, but it cannot confirm a sensor calibration fault or identify a damaged component.

How to fix a missing or confusing graph

1. Keep the page active. Leave the Sensors Test visible while you move the device. Browsers can pause or limit sensor updates when a tab is in the background or the screen is locked.
2. Allow motion access. Accept the browser's permission prompt if it appears. If you previously blocked access, open the browser's site controls from the address bar, find the motion or sensor permission if listed, allow it, and reload the page.
3. Check phone browser settings. On an iPhone using Safari, check Settings › Safari › Motion & Orientation Access if that option is available, then revisit the page and grant its request. On Android, check Chrome's Settings › Site settings for a motion sensor permission if your version provides one. Names and availability vary by browser and operating system.
4. Try a supported browser and a normal tab. Sensor access differs across browsers, devices, and private browsing modes. Update the browser, reload the test, and try a regular browsing tab. Windows 11 and macOS generally do not provide a single system-wide accelerometer permission switch for a browser page, so check the browser's site controls first.
5. Move the device deliberately. Keep a steady grip and use slow, clear tilts. Very small movements may be hidden by graph scaling or sensor filtering, while a loose grip can add extra movement that makes the result hard to read.
6. Restart the browser, then compare. Close and reopen the browser if sensor updates stopped. If the graph still does not respond, test another device or browser that supports motion sensors. A different result helps separate a browser limitation from a possible device issue.

What the graph cannot prove

A moving graph does not tell you that the accelerometer is perfectly accurate. It does not verify calibration, diagnose a loose internal connection, or prove that an app interpreting motion is working correctly. Browser readings may be filtered or updated at different rates, so two browsers can show different-looking graphs from the same movement.

The accelerometer also is not the same as the gyroscope. An accelerometer measures acceleration, including gravity. A gyroscope measures rotation. A page may offer both, and they can respond differently when you turn a device in place. If a motion-controlled app behaves oddly, compare the accelerometer and gyroscope readings if both are available, then check the app's own controls and calibration options.

Try the test with the device resting on a firm surface before deciding that an active graph signals a problem.