The World Magnetic Model

The World Magnetic Model is a product of the United States National Geospatial-Intelligence Agency (NGA). The U.S. National Geophysical Data Center (NGDC) and the British Geological Survey (BGS) produced the WMM with funding provided by NGA in the USA and by the Defence Geographic Imagery and Intelligence Agency (DGIA) in the UK.

The World Magnetic Model is the standard model of the US Department of Defense, the UK Ministry of Defence, the North Atlantic Treaty Organization (NATO), and the World Hydrographic Office (WHO) navigation and attitude/heading referencing systems. It is also used widely in civilian navigation systems. The model, associated software, and documentation are distributed by NGDC on behalf of NGA. The model is produced at 5-year intervals, with the current model expiring on December 31, 2009.

The current model, WMM-2005 (published 12/2004), is available from this web site or by contacting NGDC.