What is magnetic declination?

Magnetic declination is the angle between magnetic north (where a compass needle points) and true geographic north. It varies by location and changes slowly over time as the Earth's magnetic field shifts.

Is east declination positive or negative?

East declination is positive by convention. If your location has a declination of +10° East, magnetic north is 10° east of true north, so you add 10° to your compass bearing to get a true bearing.

Is the dipole-axis bearing a magnetic declination estimate?

No. A compass aligns with the local horizontal magnetic-field component, not a line to one magnetic pole. Use the official NOAA World Magnetic Model (WMM) or IGRF calculator for declination.

How fast does magnetic declination change?

Declination changes at roughly 0.1°–0.5° per year depending on location, with some high-latitude areas changing faster. Maps and instruments should be updated every 5–10 years; the WMM is refreshed every 5 years.

What is the difference between declination and dip (inclination)?

Declination is the horizontal angle between magnetic north and true north. Dip (or inclination) is the vertical angle — how steeply the field lines plunge into the Earth. Compasses measure declination; dip meters measure inclination.

Why does declination vary so much by location?

The Earth's magnetic pole is not at the geographic pole, and the field is also distorted by variations in the iron-rich rock inside the Earth. Locations near the magnetic pole or large mineral deposits experience larger or more locally variable declination.

Magnetic Declination Calculator

Enter coordinates to illustrate a centered-dipole axis bearing; do not use the result as magnetic declination for navigation.

Location Input

Quick pick — major city

or enter coordinates

Latitude (−90 to 90)

Longitude (−180 to 180)

Educational geometry only — not a navigation declination.

Result

Pick a city or enter coordinates, then click Calculate.

Summary

Enter coordinates to illustrate a centered-dipole axis bearing; do not use the result as magnetic declination for navigation.

How it works

Select a major city from the dropdown or enter latitude and longitude manually.
The calculator finds the great-circle bearing toward an illustrative centered-dipole axis.
In official charts, positive (East) declination means magnetic north lies east of true north and is added to a magnetic bearing to get true bearing.
In official charts, negative (West) declination means magnetic north lies west of true north and is subtracted from a magnetic bearing to get true bearing.
Use NOAA WMM or IGRF output—not this illustration—for compass correction or navigation.

Use cases

Understand why a single magnetic-pole coordinate cannot supply operational declination.
Compare a centered-dipole illustration with an official WMM result.
Teach students the concept of magnetic declination and its geographic variation.
Teach the distinction between a geometric pole bearing and the local horizontal magnetic field.
Locate official NOAA WMM/IGRF resources before doing navigation work.
Demonstrate how an assumed dipole axis varies from true north by location.

Frequently Asked Questions

Last updated: 2026-09-19 · Reviewed by Nham Vu