Methodology

How the heading is interpreted

A browser orientation event is useful only when its reference is known. Online Compass separates north-referenced readings from relative rotation and from angles entered by hand.

North-referenced sensor data

On iOS, a valid webkitCompassHeading is treated as a magnetic-north bearing. Elsewhere, the tool uses an orientation event marked absolute while the device is nearly flat. The browser's absolute reference may be magnetic or true north; this tool does not claim which. Screen rotation is applied so the displayed heading follows the top of the visible screen.

Relative and manual data

A relative orientation event measures rotation from a browser-defined starting frame. It cannot establish north, so the dial does not show cardinal labels for that state. The manual control is an angle chosen by you and is always marked unverified.

Accuracy and limitations

If the device reports an accuracy estimate, the tool displays that estimate rather than inventing one. Small sensor changes are damped to reduce jitter. Readings clear when the tab is hidden, the screen rotates, or updates stop. Nearby magnetic objects and device calibration can still produce a wrong direction. The optional True North mode adds a local WMM2025 declination estimate to an explicitly magnetic heading. Coordinates remain in page memory; unspecified absolute references are refused. The model is valid through 2029, assumes 0 m ellipsoid height if altitude is unavailable, and refuses weak-field caution or blackout zones.