# How do you identify a mountain with a map and compass? > Take a bearing to the peak, correct for declination, draw the line on a topo map, then check distance and height. A step-by-step method that works with no battery. Source: https://mountainidentifier.org/guides/identify-mountains-with-a-map-and-compass Last updated: 2026-10-09 **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](https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml). 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 degrees) from each landmark. You're where the lines cross. Landmarks roughly 90 degrees 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](https://mountainidentifier.org/guides/how-far-away-can-you-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](https://mountainidentifier.org/guides/identify-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](https://mountainidentifier.org/guides/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](https://mountainidentifier.org/guides/what-mountain-is-this) for the other methods. ### What is magnetic declination? The angle between magnetic north, where your compass points, and true north, which maps use. It varies by place and changes slowly over the years. In parts of the US it's more than 15 degrees, enough to put you on the wrong mountain if you ignore it. ### What map scale is best for identifying mountains? A 1:50,000 or 1:62,500 map covers enough ground for peaks 20 to 40 km away while still showing summits clearly. For distant peaks, a 1:100,000 or 1:250,000 sheet helps, because the line of sight runs off a detailed map quickly. ### Can I use my phone's compass instead? Yes, for a bearing. The phone's compass app shows true or magnetic north, so check which setting you're using. Phone compasses drift near metal and magnets, so take the reading away from your car or pack frame. ### How do I know which summit on the line it is? Use height and distance together. Estimate how far away the peak looks, then check which summit on the line is tall enough to be seen over everything in front of it. Snow cover and shape help confirm it. --- Peak data (c) OpenStreetMap contributors, licensed ODbL. Mountain Identifier: Peaks is an iOS app by Patrick Tammaro. Free to download; identifying peaks is part of the Pro subscription. App Store: https://apps.apple.com/us/app/mountain-identifier-peaks/id6752865266