Magnetic Declination Calculator
Convert between true north and magnetic north.
Apply the correct declination to your compass bearing for accurate navigation anywhere in the world.
Magnetic declination (also called magnetic variation) is the angle between true north (geographic north pole) and magnetic north (where a compass needle points). It varies by location and changes slowly over time as Earth’s magnetic field shifts.
The conversion is simple:
- Magnetic bearing = True bearing − Declination (east declination is positive, west is negative)
- True bearing = Magnetic bearing + Declination
East declination means magnetic north is east of true north — your compass reads too high (add to get true bearing, subtract to get magnetic). West declination means magnetic north is west of true north — your compass reads too low.
A helpful mnemonic: “East is least, west is best”
- East declination: subtract from true bearing to get magnetic bearing
- West declination: add to true bearing to get magnetic bearing
Typical declination values around the world (approximate, 2025):
- New York, USA: −13° (west)
- London, UK: −0.5° (near zero)
- Sydney, Australia: +13° (east)
- Vancouver, Canada: +17° (east)
- Moscow, Russia: +11° (east)
- Cape Town, South Africa: −26° (west)
- Tokyo, Japan: −8° (west)
- Chicago, USA: −3° (west)
Annual change: Declination changes by about 0.1°–0.3° per year in most locations. Maps and charts show the declination at their publication date plus the annual rate of change. Always use the current value for precise navigation.
For exact current values at any location, use the World Magnetic Model (WMM) published by NOAA and the British Geological Survey.