About this tool
Every modern phone carries an accelerometer, a gyroscope, a magnetometer and a GPS receiver, and the browser can read all four through standard web APIs — DeviceMotionEvent, DeviceOrientationEvent and watchPosition. This page turns those readings into a phone sensor test you can run without installing anything — whether you came for a gyroscope test online, an accelerometer test, a compass test, a GPS accuracy test, a vibration test or a bubble level online: one card per sensor, each with its own Start button, live numbers in monospace with units, a small chart of the last few seconds, and the sample rate the browser is actually handing to the page. It is meant for the moments when a map keeps pointing the wrong way, a racing game drifts on its own, navigation jumps around, or you are checking a second-hand phone before paying for it. The whole thing runs on the phone: no coordinates, no readings and no report ever leave the browser.
What each card measures
The accelerometer card shows x, y and z both with and without gravity, plus the interval the browser reports. Lying still on a table, the length of the gravity vector should sit close to 9.81 m/s²; a deviation beyond the reference threshold is flagged as “worth checking”, never as “broken”. The bubble level uses the same gravity vector to compute pitch and roll, with a “zero at current position” button so you can level against a surface you trust. The gyroscope card shows the three rotation rates and a “lay flat for 5 seconds” measurement that reports the resting offset (bias) and noise — a large bias is what makes AR and games drift when the phone is not moving. The compass card shows the magnetic heading on a compass rose, compensated for screen rotation, with the accuracy where the platform reports one, and a static figure-8 calibration diagram. The GPS card shows latitude and longitude, horizontal accuracy in metres, altitude, speed, heading, time to first fix and an accuracy-over-time chart. The vibration card fires a few preset patterns and anything you type in. A small screen-orientation card completes the set.
The five-second still test and its four verdicts
Both the accelerometer and the gyroscope have a short measurement where you put the phone down and wait. The result is one of four verdicts. “OK” means the average sat within the reference threshold. “Check” means the resting value is off — a gravity reading far from 9.81 m/s², or a gyroscope bias above 1 °/s — and the sensor may want calibrating. “Moving” means the readings varied too much to judge, almost always because the phone was picked up or the table was bumped; just run it again. “Not enough samples” means the browser delivered fewer than ten readings in the window, which happens when a tab is throttled or a permission was granted late. The thresholds (±0.5 m/s² for gravity, 1 °/s for gyroscope bias) are reference values chosen conservatively, not manufacturer specifications.
What this page cannot tell you
The sample rate shown is the rate the browser gives to a web page, which is often lower than what the sensor itself can do, so it describes your browser, not your hardware. A compass is a magnetometer, and it is thrown off by magnets in phone cases and car mounts, by nearby metal and by speakers; a wrong heading usually means interference, not a faulty sensor. The compass shows magnetic north, which differs from true north by the local declination. GPS accuracy indoors or between tall buildings is poor on every phone, and the browser may fall back to Wi-Fi or cell-tower positioning — the accuracy field will reflect that with a much larger number. iPhones have no vibration API in any browser, so that card cannot run there. And the verdicts above are simple readings against reference thresholds: this page does not diagnose hardware faults and will not tell you that a part has failed.
On a desktop
Most laptops and desktops have no motion sensors, so if you open this page on a computer it shows the page URL and a QR code to scan with your phone; the cards stay below so you can still read what each one does. GPS may still work on a laptop through Wi-Fi positioning, usually with an accuracy of tens to hundreds of metres.
Your location stays on your phone
There is no map, because drawing one would send your coordinates to a tile server. Coordinates are shown to three decimal places by default — roughly 100 m — and you tap a button to see six. The report produced by the Copy button contains the verdicts, sample rates, fix count, time to first fix and accuracy figures only; it never includes latitude, longitude, altitude, speed or heading, and nothing is sent anywhere. Analytics record which cards were started, never a value.