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CrowdMag: Crowdsourced magnetic data

Models are joint research with:
The Cooperative Institute for Research in Environmental Sciences (CIRES).

Magnetic Declination

Magnetic declination, sometimes called magnetic variation, is the angle between magnetic north and true north. Declination is positive east of true north and negative when west. Magnetic declination changes over time and with location. As the compass points with local magnetic fields, declination value is needed to obtain true north.. more
Compute the declination for specified date and location

Declination

Based on the World Magnetic Model (WMM) and the International Geomagnetic Reference Field Model (IGRF)
(Backup Calculators: WMM / IGRF)

Calculate

Turn your phone into a magnetic compass and calculate declination at this page

Compass Webapp

Turn your phone into a magnetic compass and calculate declination at this page

Compass

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Magnetic Poles

Magnetic declination (D) is unreliable near the poles.

Learn More

Download Pole Locations

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Declination Map Viewer

Displays historical isogonic lines calculated for the years 1590-2015.

Viewer

Download Historic Maps

Magnetic Declination
By NCEI Scientist Patrick Alken

Common Questions

  • How do I correct my compass to the true bearing?

    You can compute the true bearing from a magnetic bearing by adding the magnetic declination to the magnetic bearing... more

  • Does the compass needle point toward the magnetic pole?

    No. The compass points in the directions of the horizontal component of the magnetic field where the compass is located, and not to any single point... more

More: Geomagnetism Frequently Asked Questions