Magnetic Declination Estimator
Estimate the magnetic declination (difference between true north and magnetic north) for a given location using a simplified model.
Results
What is it?
Magnetic declination is the angle between geographic true north (the direction to the North Pole) and magnetic north (the direction a compass needle points). It varies by location and changes slowly over time due to shifts in Earth's molten core. Positive declination means magnetic north is east of true north; negative means it is west.
How to use
Enter your latitude, longitude, and the current year. The result is a simplified estimate of local magnetic declination. For navigation-critical applications, use the NOAA World Magnetic Model (WMM) online calculator for precise values accurate to within 1 degree.
Example scenario
London (51 N, -0.12 W) in 2024: estimated declination approximately -1.6 degrees. In practice, the UK Ordnance Survey publishes precise values ? currently around -0.5 to +1 degree depending on location. Western USA has declinations of +12 to +18 degrees East, requiring significant compass correction.
Pro tip
This is a simplified approximation. Use NOAA World Magnetic Model for precise values. Positive = east of true north. Always convert between magnetic and true bearings before navigating: Mag to True, add East declination. The UK declination is currently small (~1 degree) but eastern USA and western Canada have large declinations requiring significant correction for accurate compass navigation.