Loading page
About this tool
Sanity-check the bias in your device's accelerometer and gyroscope.
The Device Sensor Calibration Checker streams your phone's motion sensors through the browser's DeviceMotion API and logs a timestamped row for each sample: accelerometer X, Y and Z including gravity, to three decimals, plus the combined gyroscope rotation-rate magnitude across alpha, beta and gamma. Rest the device on a flat surface and the readings tell you whether its sensors sit near their expected at-rest values or carry a visible bias. It is a quick sanity check for anyone whose compass drifts, whose step count looks wrong, or who wants to see raw sensor output before blaming an app.
Open Device Sensor Calibration Checker on AltFTool — it loads instantly in your browser.
Lay the phone flat and still, press "Start with permission" and allow motion access when the browser asks.
Watch the Live local readings table add one timestamped row per sample: accelerometer X, Y and Z including gravity to three decimals, plus the combined rotation-rate magnitude.
Check that a face-up handset reads about 9.8 on the Z axis with X, Y and the rotation rate near zero, then press "Stop sensor".
Shows the actual per-axis accelerometer values and rotation-rate magnitude so you can judge drift yourself instead of trusting a pass badge.
Keeps a continuous timestamped stream of the most recent samples, so a bias that only appears intermittently still shows up in the history.
Nothing starts until you press start and grant motion access, and the readings stay in the page — they are never uploaded.
With the device face up and still, the Z axis should sit near 9.8 m/s² — one g — while X and Y hover close to zero and the rotation rate stays near zero. A persistent offset from those values on a motionless device is the bias you are looking for.
iOS and other modern browsers require an explicit user gesture and a permission grant before releasing DeviceMotion data, and the page only works in a secure context. If permission is declined or the browser exposes no motion sensor, it says so rather than showing zeros.
Two: the accelerometer, reported as acceleration including gravity on the X, Y and Z axes, and the gyroscope, reported as a single rotation-rate magnitude combining the alpha, beta and gamma rates. Browsers do not expose a raw magnetometer through this API.
No — it observes what the sensors report but cannot write calibration values back to the device. Use it to spot a problem, then recalibrate through your phone's own settings or compass app, and treat the readings as approximate rather than safety-certified measurements.