Magnetic Declination Calculator

Declination correction from location and date.

Latitude (°N)

Longitude (°E)

Magnetic bearing (°)

Years from 2025

Tab to move between fields

Magnetic declination (°)

175.45

True bearing (°)175.45

Magnetic bearing from true (°)184.55

Secular variation (°/yr)-0.05

Magnetic inclination (°)59.21

Grid convergence (°)-3.86

Pole Lat Rad1.51

How to Use This Calculator

Enter your geographic Latitude (°N) and Longitude (°E) — negative values for south latitude and west longitude.
The calculator returns Magnetic declination (°): positive means magnetic north is east of true north, negative means west.
Enter a Magnetic bearing (°) from your compass to get the corrected True bearing automatically.
Adjust Years from 2025 to account for secular variation when using older maps or planning future expeditions.
Use the Magnetic inclination (°) output to understand how steeply the field dips at your location.

How the result changes with Latitude (°N)

Latitude (°N): Geographic latitude in degrees. Positive = North, Negative = South.
Longitude (°E): Geographic longitude in degrees. Positive = East, Negative = West.
Magnetic bearing (°): Compass bearing to convert between magnetic and true north.
Years from 2025: Years before (negative) or after (positive) the 2025.0 epoch for secular variation.

Magnetic declination (°): Angle between true north and magnetic north. Positive = East, Negative = West.
True bearing (°): True (geographic) bearing computed from the magnetic bearing plus declination.
Magnetic bearing from true (°): Magnetic compass bearing if the input bearing were a true bearing.
Secular variation (°/yr): Estimated annual rate of change in declination at this location.
Magnetic inclination (°): Dip angle of the magnetic field below horizontal (dipole approximation).
Grid convergence (°): Approximate difference between grid north and true north for UTM grids.

Identify Input Parameters
4 parameters
Latitude (°N) = 40, Longitude (°E) = -105, Magnetic bearing (°) = 0, Years from 2025 = 0 = 4 input(s) provided
Calculate Magnetic declination
175.45 = 175.45
Calculate True bearing
True bearing = magneticBearing + declination
175.45 = 175.45
Calculate Magnetic bearing from true
Magnetic bearing from true = magneticBearing - declination
184.55 = 184.55