Magnetic declination calculator

Date

The range of dates permitted with the International Geomagnetic Reference Field (IGRF-12) ranges from 1900 and 2020.

Latitude and Longitude

When entering the geographic latitude or longitude use one of the following three conventions:

• Decimal degrees to a maximum of three decimal places, e.g., 45.738. Choose North or South, East or West from the 'radio' buttons.
• Degrees and minutes, e.g. 45 54.3. Choose North or South, East or West from the 'radio' buttons.
• Degrees, minutes, and seconds, e.g. 45 54 3.3. Input seconds will be rounded to the nearest second in the output. Choose North or South, East or West from the 'radio' buttons.

Grid declination

Grid Declination is defined as the angle of magnetic North relative to grid North where grid North is referenced to the grid lines shown on navigation charts with a Tranverse Mercator projection for a UTM coordinate system. The grid convergence angle is also supplied when grid declination is selected. The grid convergence angle is the angle of grid North relative to True North.

For more information on grid declination and the grid convergence angle, please refer to the following pages:

• Magnetic declination
• Using a compass