Magnetic

Magnetic declination and true and magnetic bearings.

These tools give magnetic declination from the World Magnetic Model or IGRF, the angle from grid north to magnetic north, and conversions between true and magnetic bearings. Pilots, hikers, surveyors retracing old bearings, and drone operators calibrating compasses use them. Start with magnetic declination for your place and date. Declination changes year to year, so an old chart's variation or an old deed's bearing needs the date it was true.

I want to find the magnetic declination

Magnetic declination
Magnetic declination (variation), inclination, and field strength at any place and date from the World Magnetic Model 2025 or IGRF-14, with the model's uncertainty and compass warning zones.

I want to convert a bearing between true and magnetic

True and magnetic bearings
Converts a true bearing to magnetic or back, with a chart variation like 12°W, the magnetic model at a place and date, or both side by side.

I want to find the angle from grid north to magnetic north

Grid variation (grivation)
The angle from grid north (UTM or UPS) to magnetic north, for navigating by a grid near the poles or on military maps: declination minus grid convergence, with the sign convention stated.

Guides that use these tools

VFR cross-country: Distance and true course between two airports, the heading to fly into the wind, the magnetic heading, and the time en route.
IFR approach brief: The weather, the holding speed, the entry, the wind-corrected hold, and the visual descent point.