GPS & Compass

This tool uses two browser APIs that communicate directly with your device's hardware — no data ever leaves your device.

GPS (Geolocation API)

The navigator.geolocation.watchPosition() call requests continuous position updates from your device's GPS receiver (or Wi-Fi/cell triangulation when GPS is unavailable). It returns latitude and longitude in decimal degrees, plus altitude (meters above the WGS-84 ellipsoid), position accuracy radius, and ground speed in meters per second.

Accuracy depends on the signal source: GPS outdoors typically achieves ±3–10 m; Wi-Fi positioning indoors is usually ±15–50 m; cell tower fallback can be ±500 m or worse.

Altitude is GPS-derived and can be off by 10–50 m even with good sky visibility. It is not reported on all devices.

Speed is only available while moving and is not reported when the device is stationary.

Compass (DeviceOrientation API)

The compass heading comes from the device's magnetometer and gyroscope via the DeviceOrientationEvent. When the event is marked absolute (or when webkitCompassHeading is available on iOS), the heading is relative to true or magnetic north. Otherwise it is relative to the device's arbitrary start orientation.

Some browsers, Safari on iPhone and iPad among them, will only share the compass after you tap to allow it — that's what the "Enable Compass" button is for. Where the browser shares it without asking, the button does not appear.

Metal objects, electronics, and magnetic cases near the device can deflect compass readings. For best accuracy, hold the device flat and away from metal surfaces.

Coordinate formats

Coordinates are shown in both DMS (degrees, minutes, seconds) and decimal degrees. Decimal degrees are the standard for GPS software and map URLs. The copy button copies decimal degrees suitable for pasting into Google Maps, Apple Maps, or any geocoding service.