Magnetic declination is an important concept for accurate navigation. A compass will always point along the lines of magnetic force (which converge on what are called the magnetic poles). The angle between the direction of force and the direction of the geographic north pole is called the declination. If a compass at your location is pointing to the right of true north, declination is positive or east, and if it points to the left of true north, declination is negative or west. As one moves across the surface of the globe, lines of constant magnetic declination are called isogonic lines.

As the earth's magnetic field varies over time, the positions of the north and south magnetic poles gradually change. The magnetic declination at a given location also changes over time.

This map displays historical isogonic lines and magnetic poles calculated for the years 1590-2025.
Model description:

• Years 1590-1890: calculated from the gUFM model
• Years 1900-2025: calculated from the IGRF
• Years 1890-1900: a smooth transition was imposed between models

More information about geomagnetism at NCEI

More information about magnetic poles and polar wander at NCEI

Instructions for using the map:

• Use the time slider to select a year (1590-2025).
• Click on a line to identify the declination value.
• Zoom in and out using the zoom slider or the + and - keys.
• Toggle the isogonic lines, modeled pole locations, historical modeled pole track, and observed pole locations with the checkboxes on the left.
• View the map in Global Mercator, Arctic, or Antarctic views by clicking the tabs at the right of the screen.
• Using the menus in the upper-right, select various basemaps, and toggle boundaries/labels and latitude/longitude lines (graticule).

Basemap/reference layers:

• GEBCO_2021 Basemap (NOAA NCEI Visualization): A shaded-relief visualization of the GEBCO_2021 Grid. This visualization of the GEBCO_2021 grid was produced by NOAA/NCEI. More information on NOAA's GeoPlatform.
• GEBCO_2021 Grayscale Basemap (NOAA NCEI Visualization): A shaded-relief visualization of the GEBCO_2021 Grid. This visualization of the GEBCO_2021 grid was produced by NOAA/NCEI. More information on NOAA's GeoPlatform.
• Light Gray: Esri Light Gray Canvas
• Dark Gray: Esri Dark Gray Canvas
• Arctic Basemap: A visualization of the IBCAO v4 and GEBCO_2020 grids. More information on NOAA's GeoPlatform. Arctic
• Antarctic Basemap: A visualization of the IBCSO and GEBCO_08 grids. More information on NOAA's GeoPlatform.
• Imagery: Esri World Imagery
• Ocean: Esri Ocean Basemap
• National Geographic: Esri/National Geographic Basemap

Map projections:

• Global view: WGS84 Web Mercator (Auxiliary Sphere); EPSG:3857
• Arctic view: WGS84 Arctic Polar Stereographic; standard parallel of 71 degrees; EPSG:3995
• Antarctic view: WGS84 Antarctic Polar Stereographic; standard parallel of -71 degrees; EPSG:3031

Version: 3.1.1, last updated 2023-06-02