How to Use a Compass

A map and compass don't need batteries, a signal or a charger. A phone or GPS is a great tool, but when it dies, gets wet or loses signal in a canyon, a compass and the skill to use it are what get you home. This guide covers a standard baseplate compass, the kind most hikers, hunters and paddlers carry.

The Parts of a Baseplate Compass

Baseplate: the clear, flat plate everything sits on. Its straight edges and ruler are for working on a map.
Direction-of-travel arrow: the arrow on the baseplate that points the way you're going.
Magnetic needle: the red end points to magnetic north. The other end points south, so always go by the red end.
Rotating bezel (dial): the ring marked in degrees from 0 to 360. North is 0 (or 360), east 90, south 180 and west 270.
Orienting arrow: the outline arrow inside the bezel that turns with it. Lining the red needle up inside it is called putting "red in the shed."
Orienting lines: the parallel lines inside the bezel, which you line up with the north–south lines on a map.
Index line: the mark at the top of the bezel, at the base of the direction-of-travel arrow, where you read your bearing.
Declination adjustment: on better compasses, a small screw or dial that offsets the orienting arrow so you don't have to do declination math in your head.

True North, Magnetic North and Declination

Your map is drawn to true north, the North Pole. Your compass needle points to magnetic north, which is somewhere else. The angle between the two where you're standing is the declination. Across Canada and the U.S. it ranges from almost nothing to more than 15 degrees, east or west, and it slowly changes from year to year.

Find your declination in your map's legend (and note the year it was printed), or look up today's value with NOAA's declination calculator or Natural Resources Canada's magnetic declination page.
Set it once on your compass if it has a declination adjustment. Then every bearing you read is already a true bearing that matches your map.
No adjustment? Convert by hand. To go from a map (true) bearing to a compass (magnetic) bearing, subtract east declination and add west declination: "east is least, west is best." Do the opposite to go from compass to map.

Ignore declination and every bearing is off by that many degrees. At 10 degrees, you'd miss a target a kilometre away by about 175 metres.

Take a Bearing to Something You Can See

Hold the compass flat at your waist or chest, with the direction-of-travel arrow pointing straight at the landmark.
Turn the bezel until the orienting arrow sits under the red end of the needle: red in the shed.
Read the bearing at the index line. With declination set, that's your true bearing to the landmark.

Follow a Bearing

Set the bearing you want at the index line.
Hold the compass flat in front of you and turn your whole body until the red needle sits in the orienting arrow.
The direction-of-travel arrow now points your way. Sight along it to a tree, rock or other landmark on that line.
Walk to that landmark, then repeat. Don't walk staring at the compass; you'll drift. Leapfrog from landmark to landmark.

Obstacle in the way? Sight a landmark on the far side, walk around to it and carry on, or box around the obstacle with 90-degree turns, counting your paces out and back.

Take a Bearing From Your Map

Lay the compass on the map with one long edge of the baseplate joining where you are and where you want to go, and the direction-of-travel arrow pointing toward your destination.
Turn the bezel until the orienting lines are parallel to the map's north–south lines, with the orienting arrow pointing to the top of the map (north). Ignore the needle for this step.
Read the bearing at the index line. If your compass is set for declination, use it as is; if not, convert it as described above.
Follow it using the steps above.

Orient Your Map

An oriented map lines up with the land around you, so the trail that runs to your left on the map runs to your left on the ground. Set the bezel to north (0) at the index line, lay the compass on the map with its edge along a north–south line, and turn the map and compass together until the red needle sits in the orienting arrow.

Find Where You Are: Triangulation

Pick two or three landmarks you can see and find on the map, such as a peak, a tower or the end of a lake, ideally 60 to 90 degrees apart.
Take a bearing to the first one.
On the map, put one edge of the compass on that landmark. Without touching the bezel, turn the whole compass until the orienting lines are parallel to the map's north–south lines, with the orienting arrow pointing to map north. Draw a line along the edge, back from the landmark toward you. You're somewhere on that line.
Repeat with the second landmark. You're where the lines cross. A third bearing usually makes a small triangle, and you're probably inside it.

Common Mistakes

Metal and electronics nearby. A vehicle, belt buckle, knife, phone, radio or the magnet in a phone case can pull the needle off. Step away before taking a reading.
Forgetting declination, or adding it when you should subtract it.
Not holding the compass level, so the needle drags instead of swinging freely.
Following the needle instead of the bearing. The needle always points north, not where you're going.
Reading the wrong end of the needle. Red in the shed, every time.
Using an old map's declination without checking how much it has changed.
Trusting the compass over the terrain. If a bearing says the lake is on your left and it's plainly on your right, stop and recheck.

Practice Before You Need It

Practise in a park or a familiar trail: take bearings, follow them and find your way back to where you started.
Try an orienteering event. Local clubs, such as those listed by Orienteering Canada and Orienteering USA, run beginner courses.
Carry a topographic map of the area in a waterproof bag, plus a pencil, and keep your phone's offline maps and a battery bank as a backup, not the plan.

More reading: REI's navigation basics guide. On the water? See Marine Navigation & Compass.