How to use a compass

Before discussing how to use a compass and map together, we'll go over using a compass by itself.

Compasses have been around for a long long time and there are very good reason s for that. They can be very accurate and no batteries are required! Given a choice between a compass or a GPS I’ll take the compass every time!

To read and use a compass you’ll first need to learn the various parts of the compass.

Compass Housing - Marked with degrees, allowing you to set a bearing or azimuth.
Compass Needle – RED ALWAYS points North.
Orienting Arrow – The “house” for the North end compass needle
Direction of Travel Arrow – Points the way once you’ve rotated the housing to the proper bearing degree.

All four pieces of the compass work together so that:

When you rotate the compass housing so that the direction (same as bearing and azimuth) that you want to go is where the direction of travel-arrow meets the housing you’re set.

Or said another way

The needle is giving you a steady reference point while the rest of the compass allows you to measure other directions.

What is North and how to find it.

True North – (Sometimes called Geographic North or Map North) is a precise geographic point at the north pole where all longitude lines meet. Maps are laid out with true north at the top.

Unfortunately, true north is not the same as magnetic north which is where your compass is pointing.

Magnetic North - The red end of your compass needle is magnetized and wherever you are, the earth's magnetic field will cause the needle to rotate until it lies in the same direction as the earth's magnetic field. Magnetic North is marked with an MN on topographic maps.

Unless you’re fortunate enough to live in an area with no deviation between true and magnetic north you’ll need to adjust your compass for it.

Declination – The measurement of difference between True North and Magnetic North

As you can see in this USGS chart from 2000 the amount of declination varies by region.

Declination near Cincinnati, OH is about 4 degrees where the declination near Seattle, WA is about 18 degrees.

Seattle Declination East Fork Declination

And to make it even more confusing, declination changes over time. Check out this USGS movie showing how magnetic fields shift.

Common Problems When Using a Compass

Make sure the RED end of the needle is pointing at North. If the south end of the needle points to north you’ll go in the opposite direction of where you want. Double check!

Keep your compass AWAY from metal objects. Look at the photos below to see the change the Gerber Multi Tool caused in the north arrow.

GOOD - No metal nearby BAD - Metal changing bearing

The needle is magnetized so if you have anything metallic nearby it will cause the needle to point someplace other than north.

More Compass Tips and Helpful Hints:

Compass Care and Usage
Compass Definitions

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