World Magnetic Model

The World Magnetic Model (WMM) is a standard model of the core and large-scale crustal magnetic field. It is the standard model for navigation, attitude, and heading referencing systems that use the geomagnetic field. The WMM is also used for civilian applications, including navigation and heading systems. A new version of the model is updated every five years to address changes in Earth’s magnetic field. The current version (WMM2025) was released on December 17, 2024, and will remain valid until late 2029. The current model WMM2025 is produced jointly by the NCEI and the British Geological Survey (BGS). The model, associated software, and documentation are distributed by NCEI on behalf of US National Geospatial-Intelligence Agency and by BGS on behalf of UK Defence Geographic Centre.