World Magnetic Model 2020 Calculator

Use the tool below to compute values for the geomagnetic field and secular variation for a given set of coordinates and date. This calculator uses the World Magnetic Model as released in Dec 2019.

Choose the geodetic latitude and longitude either by entering the coordinates into the form below (decimal degrees may be entered into the 'degrees' field, and degrees S or W should be entered with a negative sign), or by simply clicking the location on the map. The altitude and date may be set using the appropriate form fields.

Clicking on the 'Show result on map' button will display the values for the chosen coordinates in a pop-up window. These results may be saved by clicking on the 'Save' button allowing you to compare values from a number of locations.

As this is based on a web service you can also obtain results in XML format using an HTTP GET request
http://geomag.bgs.ac.uk/web_service/GMModels/wmm/2020/?latitude=-80&longitude=240&altitude=0&date=2022-07-02&format=xml modifying the query string parameters as appropriate.

Geodetic Coordinates

Latitude:	(See note 1)
Longitude:	(See note 1)
Altitude:	km above MSL

Date

Date: (See notes 2 and 3)

Specify latitude and longitude as one of:

Examples	Description
40�44'55"N 40:44:55S 73 59 11W	Degrees, minutes and seconds suffixed with 'N'/'S' (for latitude) or 'E'/'W' (for longitude) to indicate the hemisphere. Degree, minute, and second values can be separated either by the standard symbols for angles (�, ' and ") or by colon characters (:) or by spaces. Negative numbers may not be used. Degree, minute and second values must all be integers - no decimal values are allowed
40.7486 -40.7486 -73.9864	Signed decimal degrees without compass direction ('N'/'S' or 'E'/'W'). Negative values indicate south latitude or west longitude.

Specify date as one of:

Examples Description

2020-01-31 Date in the form year-month-day

2020.084 Decimal year
Dates must be between 2020.0 and 2025.0

Examples	Description
2020-01-31	Date in the form year-month-day
2020.084	Decimal year

Any values that you enter that are not understood will be highlighted in yellow. Once these errors are corrected the highlight will be removed and the calculated magnetic field value displayed.

Legend
	D = Declination	I = Inclination	X = North Intensity	Y = East Intensity	H = Horizontal Intensity	Z = Vertical Intensity	F = Total Intensity
MF = Main Field	degrees east	degrees down	nT	nT	nT	nT down	nT
SV = Secular Variation	arcmin/year	arcmin/year	nT/year	nT/year	nT/year	nT/year	nT/year

Please note that for Internet Explorer 10 and earlier there may be occasional erratic behaviour from the clickable map and the pop-up window. For very old versions of Internet Explorer the results may not be visible.

Data and Services

Data

Models & Compass Variation

Space Weather

Directional Drilling

BGGM
IFR
BGGM/IFR/IIFR 1.5MB pdf

INTERMAGNET software