Magnetic Declination Calculator

True North vs Magnetic North: What is the Difference?

To navigate accurately with a map and compass, you must understand the fundamental difference between True North vs Magnetic North. These two "Norths" are not located in the same place, and failing to account for the difference will lead you off course.

• True North (Geographic North): This is the fixed point at the very top of the Earth's axis where the lines of longitude converge. When you look at a printed topographic map, the grid lines always point to True North.
• Magnetic North: This is the point on the Earth's surface where the planet's magnetic field points straight down. Because the Earth's molten iron core is constantly shifting, Magnetic North moves miles every year. Your physical compass needle always points to Magnetic North, not True North.

What is Magnetic Declination?

Magnetic declination is the angle of difference between True North and Magnetic North from your specific vantage point on Earth. Depending on where you are standing, Magnetic North might be to the East of True North (an East declination) or to the West (a West declination).

How to Find Magnetic Declination by Zip Code

Historically, hikers had to look at the "declination diagram" printed at the bottom of their paper maps. However, because Magnetic North shifts constantly, old maps have outdated declination values.

Using our calculator above, you can find the live, up-to-date magnetic declination by zip code, city name, or exact GPS coordinates. We ping the World Magnetic Model (WMM) database maintained by NOAA to give you the exact degree adjustment required for today's date.

How to Apply Declination to Your Compass

Once you calculate your local declination angle, you must apply it to your bearing:

• For West Declination: Add the declination degrees to your True bearing to get your Magnetic bearing ("West is Best, Add").
• For East Declination: Subtract the declination degrees from your True bearing ("East is Least, Subtract").

Many premium baseplate compasses feature a tiny adjustment screw that allows you to "set and forget" your local declination, automatically aligning the orienting arrow with True North.