Magnetic declination calculator (WMM2025): magnetic, true and UTM grid north
A compass points to magnetic north, which is neither true north (geographic) nor grid north (UTM). Pick the place and the date to see the magnetic declination, how much it changes per year and the angle to the grid, using the official WMM2025 model.
1 Where?
You can also click right on the map. Your location stays on your device only: nothing is sent to us (addresses are looked up on OpenStreetMap directly from your browser).
2 Date and height
WMM2025 is valid from 2025 to 2029. Height barely changes the result: you can leave it at 0.
Result
Pick the place above (or click on the map). The result shows up here instantly.
Convert a bearing
The three norths
True north is the direction of the geographic pole, along the meridians. Magnetic north is where the compass needle points, and it changes from place to place and from year to year. Grid north is the direction of the vertical lines of the UTM projection (the map's "N"); it only matches true north on the zone's central meridian.
Magnetic declination (or variation) is the angle from true north to magnetic north: positive (East) when the needle points to the right of true north, negative (West) when it points to the left. True bearing = magnetic bearing + declination. Grid convergence is the angle from true north to grid north, and the grid magnetic angle is the difference between the two.
The values come from the World Magnetic Model 2025 (NOAA and the British Geological Survey), the same model used by GPS units, phones and navigation charts. Declination is typically accurate to a few tenths of a degree; near the magnetic poles and in areas with local anomalies (iron ore, magnetic rocks, steel structures) the compass can be off by much more.
FAQ
What is magnetic declination?
It is the angle between true (geographic) north and magnetic north, where the compass points. It is East (positive) when the needle points to the right of true north and West (negative) when it points to the left.
How do I correct a compass bearing?
Add the declination: true bearing = magnetic bearing + declination (with its sign: West is negative). For the grid (UTM) bearing, also subtract the grid convergence. The converter in the result does both.
Why does declination change over time?
Because the Earth's magnetic field, generated by its liquid iron core, is always moving. In many places declination changes by a few minutes of arc per year, which is why old plans and deeds with magnetic bearings need the declination of the date they were surveyed.
What is the difference between magnetic north and grid north?
Grid north is the direction of the N axis of the UTM projection, used on maps and in E/N coordinates. It differs from true north by the grid convergence (zero on the zone's central meridian) and from magnetic north by the combination of both differences.
Is the result valid for any date?
WMM2025 covers 2025 to 2029. For older dates (bearings on old deeds and plans) you need the historical IGRF model.