Geomagnetism

Instructions for the WMM Declination Calculator

Values are computed using the current World Magnetic Model. Values are estimates based on the WMM2010 and are generally accurate to within 30 minutes of arc for D and I and 100-250 nT for the force elements (F, H, Z, X, and Y).

Input required is:

1. Location (latitude and longitude), entered in decimal degrees.
   note: If you do not know your latitude and longitude and you live in the United States, enter your location in the box provided and use the "Go" button.
2. Elevation (recommended for aircraft and satellite use) in feet, meters, or kilometers above WGS-84 reference ellipsoid. Elevation values are valid down to -10 km. Use the radio button to choose an appropriate unit.
3. Date in Year, Month, Day (form defaults to the current day).
4. To compute your field values, hit the Compute! button. The calculator will also compute values upon hitting the Go button.

Results:

• Declination (D) positive east, in decimal degrees
  Annual change (dD) positive east, in decimal minutes per year