How do you identify a mountain with a map and compass?

Point your compass at the mountain and read the bearing. Correct it for magnetic declination, then draw a line at that bearing on a topographic map, starting from your position. The mountain is the summit along that line whose height and distance fit what you see. If you don't know exactly where you are, take bearings to two known landmarks first to fix your position.

What you need

• A baseplate compass (the clear rectangular kind with a rotating dial). A phone compass works for the bearing, as long as you check its north setting.
• A topographic map covering the direction you're looking, far enough out to include the mountain. Distant peaks can be off the edge of a detailed sheet.
• Your declination, printed in the map margin or from NOAA's declination calculator. Map margins can be decades old, and declination drifts.

The method, step by step

1. Know where you are. Mark your position on the map. If you're unsure, see the section on fixing your position below.
2. Take the bearing. Hold the compass flat, point the direction-of-travel arrow at the summit, and turn the dial until the orienting arrow sits under the red end of the needle. Read the bearing at the index line.
3. Correct for declination. Convert your magnetic bearing to true. With east declination, add it; with west declination, subtract it. Many compasses have an adjustment screw that does this for you.
4. Draw the line. Place the compass edge on your position, align the orienting lines with the map's north-south grid, and draw a line outward along the edge. Extend it with a straight edge if needed.
5. Look along the line. Every summit it passes near is a candidate. Note each one's height and distance from you.
6. Pick the one that fits. The mountain you see has to be high enough to show over everything closer to you along the same line. If three peaks sit on your bearing, the far one is only visible if it's tall enough to clear the nearer two.

Fixing your position with two bearings

If you don't know exactly where you are, use two landmarks you can identify on the map, such as a lake outlet, a fire lookout, or a summit you're sure of. Take a bearing to each, convert both to true, and draw the back bearing (the bearing plus or minus 180°) from each landmark. You're where the lines cross. Landmarks roughly 90° apart give the sharpest fix.

Checking with height and distance

Two summits on the same bearing can be told apart by how they sit in the view. A distant peak appears lower than its real height, both because it's farther away and because the curve of the Earth hides its base; at 50 km the bottom 130 m or so is already below the horizon. Our guide to how far you can see a mountain has the full table. A clinometer, or the inclinometer in a phone compass app, gives you the angle above horizontal to compare against.

The same method works backward on a photo. If you know where it was taken, you can draw the line of sight on a map from the photo instead of the view; see identifying a mountain from a photo.

Why this is still worth learning

Batteries die and phones lose their compass calibration in the cold. A map and compass need neither, which is why they're the core of identifying peaks without signal. And understanding the method makes you better at using an app, because you'll recognize when its labels have drifted.

How an app automates the same steps

An AR identifier does exactly this, many times a second. Mountain Identifier: Peaks takes your GPS position instead of a marked map, your phone's compass heading instead of a baseplate, and checks every summit within 80 km against terrain data, the digital equivalent of "high enough to show over everything in front". When the compass is off, every label shifts sideways by the same amount, just as a bad bearing shifts your pencil line; a one-finger drag lines them back up. The live view is part of the Pro subscription.

If you're new to the topic, start with what mountain is this for the other methods.

Frequently asked questions