Magnetic Declination Calculator
Calculate the magnetic declination for any location on Earth and learn how it affects navigation
Major Global Locations
New York
Declination: -13.2°
Location: 40.7128°, -74.006°
London
Declination: -1.42°
Location: 51.5074°, -0.1278°
Tokyo
Declination: -7.47°
Location: 35.6762°, 139.6503°
Sydney
Declination: 12.3°
Location: -33.8688°, 151.2093°
Cape Town
Declination: -24.9°
Location: -33.9249°, 18.4241°
Navigation Guide
Adjusting for Declination
When the declination is West (negative): Add the declination to your compass bearing
When the declination is East (positive): Subtract the declination from your compass bearing
Example
If your intended bearing is 90° and declination is 10° West (-10°): 90° + (-10°) = 80° compass bearing
Historical Changes
Magnetic declination values change over time due to the movement of the Earth's magnetic poles. The rate of change can be up to 1° every five years in some locations.
Key Changes (London)
- 2000: -3.21°
- 2010: -2.03°
- 2020: -1.42°
Common Mistakes to Avoid
Ignoring Local Variations
Declination can vary significantly over short distances. Always check local values rather than using regional averages.
Using Outdated Values
Magnetic declination changes over time. Using old maps or guides without checking current values can lead to navigation errors.
Incorrect Adjustment Direction
Adding when you should subtract (or vice versa) can double your error. Always double-check your calculations.