How to take map bearings for land navigation

| February 4, 2015

Photo: Mark Beresford

Photo: Mark Beresford


If you’re like many hikers, you’ve found that navigation with a compass is a perishable skill that’s often forgotten just when you need it most — when you think you might be lost. You may have tried to learn how to use a compass before, following the “easy” 1… 2… 3… step system, but somehow it just didn’t stick and the next time you pulled your compass out you couldn’t remember exactly what to do.

If you’re planning to stay on obvious, well-signposted trails, and you have a map, and lots of people are around, you probably don’t need a compass. But, your compass skills should be fluent before you think about going:

  • Off marked trails
  • Where the trails are hard to follow because of low use, snowfall, or long stretches of rock or sand that show no wear from foot traffic
  • Where the trails are poorly signposted
  • Where visibility could be reduced because of cloud or snowstorms

This is true even if you carry a GPS receiver, because a GPS doesn’t replace the need for a separate compass, even if it has a built-in electronic compass.

In this article, you’ll learn how to perform a common and basic navigation task — taking a map bearing. You’ll go beyond rote memorization of the steps and finally understand the principles involved. This means that you’ll be less likely to forget what to do when you’re in a tight spot and really need to get off the mountain before dark.

But first, a story to illustrate how powerful it can be to use a compass with confidence.

A story to show why you need to know how to take map bearings

I was recently doing some solo hill climbing in the beautiful Lake District of the UK, shown in the photo above. The temperature was below freezing, the wind was driving hailstones sideways, and the rocky trails were covered in a layer of ice that cracked underfoot. High up, while walking along the shore of a glacial lake, I ran into a couple of novice hikers. As we were going the same way, we hiked together for a while. The trail led up a steep slope that eventually disappeared into the snow. I checked my map and it was clear which rocky crag on the ridge we needed to head for, so we picked our own way up through the rocks.

The top of the ridge was broad and peppered with rounded knolls and big crags. There was no sign of the snow-covered trail, and it was far from obvious where to go to pick up the path that we needed on the other side. The terrain and the gale force winds on the ridge were intimidating, and the conversation soon turned to, “I’m feeling really uncomfortable” and “we should turn back now.” My new companions had a map and they knew what route they’d been following, but off the trail, they no longer knew where they were and had no compass or GPS receiver to help them find out.

I reviewed the map, took a couple of map bearings, and told them which peaks corresponded with those we saw to our left and right. This confirmed where I thought we were. I then took a map bearing along the direction we would need to walk and used my compass to show me the direction in real life. “We need to walk in this direction,” I said pointing, “and then curve around to right of this crag. In about 200m, which will take us around 5 minutes, we should find a route that will take us in this direction (gesturing), to the right of the largest peak below here on the ridge. We’ll follow that straight for about 400m while it drops down a steep slope and in around 10 minutes we should find the connecting path going this way that will take us back down to the valley.”

“Okay,” they said, “We’ll give it a few minutes and if it doesn’t look right we’ll head back the way we came.” Sure enough, within ten minutes we’d picked up a trail of rock cairns, including the one in the photo below, and the route was exactly as I’d described it.

large rock cairn near where map bearings taken

Photo: Mark Beresford

On the way down, while out of the wind, I decided to stay up on the mountain to take some photos while my companions continued on. When I looked up, I saw that they’d missed the trail and were going the wrong way. I verified this with my map and compass and then yelled down the hill to them, “Turn around, go this way (gesturing) and after the path has curved left, follow the small stream down into the valley.” With sub-freezing temperatures during the day, a night out on the mountain might have been hard to survive and I’m glad they made it down.

If you have a map and a compass and know how to use them, you have the power to predict what the trail ahead will do before you’ve ever seen it and know the direction you need to walk in. This ability is tremendously comforting and increases confidence in the outdoors like nothing else.

Now, let’s get down to business.

What are map bearings exactly?

Unlike field bearings, which you measure out in the field by pointing your compass at a real-life object, map bearings are simply bearings that you take from a map. You can take map bearings while in your house as you plan for a hike, or quickly as you go while hiking.

Map bearings are almost the same as angles, but not quite. In high school geometry class, you learned that an angle is the space between two lines at the point where they cross and that it’s measured in degrees. You learned that a right angle is 90 degrees, a straight line is 180 degrees, and a full circle is 360 degrees, and you learned to measure angles with a plastic protractor.

protractor and angle showing map bearings

Photo: Mark Beresford

A bearing has some additional, special properties that an angle doesn’t have.

A bearing is not just the space between two intersecting lines, it’s a direction. To show a direction on a map, you would draw a line while being aware that the line has two distinct ends. One end points the way you want to go and the other end points backwards. So you don’t get confused about which end is which, it can be helpful to draw an arrowhead on the end that’s pointing the way you want to go.

arrow on map showing map bearings

Photo: Mark Beresford, map: U.S. Geological Survey

Just as an angle needs two intersecting lines map bearings need two intersecting directions. The second direction is called the north-south reference. It has two distinct ends (the poles), with the end pointing towards the north labeled north and the other end labeled south. We don’t usually draw north-south reference directions because they are already on the map. But if you do need to draw one, to avoid confusion about which end is which, it’s conventional to add an arrowhead, or half-arrowhead, or a star at the north end of the line.

three norths used for map bearings

Photo: Mark Beresford

There are two more things about map bearings that make them special.

First, to measure a bearing, you have to make sure that you’ve correctly oriented both the reference direction, and the protractor you’ll use to measure the angle. By convention, the north end of the reference must always be oriented in the same direction as the zero degrees mark on your protractor. The arrangement below is therefore incorrect.

Photo: Mark Beresford

Photo: Mark Beresford

This is the correct way round.

Photo: Mark Beresford

Photo: Mark Beresford

Second, by convention, the angle is always measured in a clockwise direction from the reference. If you measure it the other way, you’ll get the bearing wrong.

Putting it all together: a map bearing is a direction measured on a map as a clockwise angle from a north-south reference direction, where the north end of the reference is aligned with 0 degrees on the protractor.

How are map bearings different from azimuths?

In the US, a bearing is often called an azimuth, especially by people who’ve been in the military. In casual use by the hiker, the terms azimuth and bearing are used interchangeably. Some references suggest some technical differences, but I wouldn’t worry about any of that — for us they mean the same thing.

The three norths

Before going on, it’s worth stating that there are three commonly used north-south reference directions. They are:

  • Magnetic north
  • Grid north
  • True north

The method of taking map bearings is the same regardless of which north reference you use. However, you do need to know which one you’re using because you have to include that information when you tell someone a bearing. It’s incomplete to tell someone to walk on a 65 degree bearing. You have to tell them to walk on a 65 degree grid bearing, or a 65 degree magnetic bearing, or a 65 degree true bearing. If you don’t tell them this, they will be left to assume and if they get it wrong they could be walking in a very different direction from the one you intended.

How to find and use these different norths on the map will covered in a future article.

Estimating map bearings

Often, when we’re out there in the real world hiking, we need to know the approximate bearing from where we are to where we want to go. Usually, we don’t have to measure it on the map, we can simply estimate it by eye with sufficient accuracy.

Here are a few examples to test yourself with. In the images, the arrowhead represents the north end of the north-south reference direction.

  1. example showing how map bearings are estimated

    Photo: Mark Beresford

    Answer: A bit less than 45 degrees, so about 40 degrees.

  2. example showing how map bearings are estimated

    Photo: Mark Beresford

    Answer: Between 90 and 180 degrees. Half way is 135 degrees, but as it’s less than half way it must be about 120 degrees.

  3. example showing how map bearings are estimated

    Photo: Mark Beresford

    Answer: Between 180 and 270 degrees. Half way is 225 degrees, but as it’s a bit more than half way it must be about 240 degrees.

  4. example showing how map bearings are estimated

    Photo: Mark Beresford

    Answer: Between 270 and 360 degrees. Half way is 315 degrees, but it’s more than half way so it’s about 330 degrees.

  5. And here is a real example from a USGS map. On a USGS map, the edge is always aligned with true north, which is our north-south reference line.
  6. Photo: Mark Beresford

    Photo: Mark Beresford

    Answer: About 110 degrees. (map credit: U.S. Geological Survey)

Estimating map bearings using compass points

When doing rough estimates, it can be easier just to use the cardinal points on the compass: north, south, east, west, and the intercardinal points in between. It’s not a bad idea to memorize the bearings in degrees for them.

compass rose

Image: Shutterstock

  • North: 0/360
  • North-east: 45
  • East: 90
  • South-east: 135
  • South: 180
  • South-west: 225
  • West: 270
  • North-west: 315

Using the cardinal system, the answers for the above five examples would be roughly:

  1. North-east
  2. South-east
  3. South-west
  4. North-west
  5. South-east

When you’re on the trail, you can use this rough method to tell a story in your head such as, “The trail will head north-west for ten minutes and then turn sharply to the south.” A one-second glance at your compass is all you then need to keep track of your progress.

Measuring map bearings with a protractor

Being able to estimate bearings from a quick glance at a map is useful for minimizing the effort needed to keep yourself located. However, if you’re planning a hiking route off trail and you need to make sure that you avoid certain obstacles, or if the cloud descends and you can’t see a thing, rough estimates won’t be good enough. To be more accurate, you need to move from estimating to measuring, and that means getting out your protractor.

The semi-circular school protractor pictured above only covers 180 degrees, which makes it unsuitable for map work. Instead, you’ll need a circular protractor like the one below.

school protractor used to take map bearings

Photo: Mark Beresford

To keep things as simple as possible, most of the examples below use graph paper instead of an actual map, but the square grid on graph paper works the same way as the square grid on a map.

In the examples, assume that you’re standing at position A and want to walk to position B.

Photo: Mark Beresford

Photo: Mark Beresford

Here’s how you measure the bearing:

  1. Turn the map so that the north end of the north-south reference is at the top.
  2. Draw a straight line that goes through positions A and B to give you the direction you want to measure.
  3. Photo: Mark Beresford

    Photo: Mark Beresford

  4. Place the center of the protractor on the A-B direction line at a point where it intersects with one of the north-south reference lines. You don’t have to center the protractor at position A. I used one of the thick blue graph paper lines as my reference line.
  5. Rotate the protractor until the 0 degrees mark lines up with the north-south reference line.
  6. school protractor used to take map bearings

    Photo: Mark Beresford

  7. Going clockwise around the degrees scale, read off the angle . In this example the map bearing is 219 degrees — and that’s your direction of travel.

Measuring map bearings with a military protractor

If you don’t fancy carrying a large pink protractor around, you can always buy a smaller, lighter military-style protractor like the one below.

military protractor used to take map bearings

Photo: Mark Beresford

If you click on the photo to enlarge it, you’ll see that the scale around the edge goes up to 6400 and not 360. This is because the military often use a different scale for measuring angles, called Mils. If you want to use degrees, you can use the numbers on the inner white band instead.

If you want an even smaller protractor that’s just marked in degrees, they are also available.

military protractor used to take map bearings

Photo: Mark Beresford

Measuring map bearings with a button compass

Some people carry a button compass in their emergency kit or have one on a flashlight or zipper pull.

button compasses not good for map bearings

Photo: Mark Beresford

If you need to take a field bearing to know that you’re going roughly east on a trail and not west, these compasses actually do the job. However, if you need to measure an accurate map bearing, don’t even bother trying with one of these. You’re better off just estimating the angle by eye as you did above.

Measuring map bearings with a USGI military lensatic compass

The USGI military lensatic compass works like a button compass in that it has the scale printed on a magnetized card that stays in place as you swivel the compass. However, its larger size means that you can actually read the scale to within a couple of degrees, and the straight edge on the left side means that you can use it to measure a map bearing.

Don’t be thrown off by the numbers on the scale. Just as with the military protractor, the military compass uses Mils on the edge of the card as its primary scale, but it also has a degrees scale just inside it.

Here’s how you measure the bearing:

  1. Place the map on a flat surface.
  2. Draw a line on the map joining the two points that you want to travel between, which in my example is the A-B line.
  3. If you think you might be confused, add an arrowhead to the line in the direction of intended travel.
  4. Place the straight edge of the compass along the north-south reference direction with the top of the compass aligned with the north end of the reference.
  5. military lensatic compass being used for taking map bearings

    Photo: Mark Beresford

  6. Without moving the compass, carefully rotate the map (together with the compass) until the black arrowhead/0 degrees mark/6400 Mils mark aligns with black line etched in the glass.
  7. military lensatic compass being used for taking map bearings

    Photo: Mark Beresford

    military lensatic compass being used for taking map bearings

    Photo: Mark Beresford

    This process is like zeroing a weighing scales before you weigh something. For example, if you want to weigh out 3oz of almonds, you first put a small bowl on the weighing scales and then press a button to make the scale read zero. Then you add the almonds to the bowl. By turning the map to align north with 0 degrees on the compass, it removes the need to subtract the before-and-after values. Remember, the north end of the reference direction must always be aligned with the 0 degrees mark on the protractor.

  8. Without moving the map even a hair, rotate and move the compass until the edge lines up with the bearing line that you drew, making sure that the lid of the compass is pointing in the direction of travel (towards B in this case).
  9. military lensatic compass being used for taking map bearings

    Photo: Mark Beresford

  10. Read the bearing off the scale at the black etched line.
  11. In the close-up you see that the bearing is around 219 degrees, which matches exactly the bearing measured by the protractors. The protractor is a more refined tool, but the more brutish USGI compass still came through.

    Photo: Mark Beresford

    Photo: Mark Beresford

In practice, when you’re climbing a hillside it can be difficult to find a surface that’s level enough to allow you to draw a line, take a measurement, and keep the map perfectly still while you rotate the compass. If you don’t need to be degree-perfect, you can rotate the compass while in a sitting position resting the map on your knees. If you have to, you can even hold the map in one hand and rotate the compass with the other while standing up, trying your best not to move the map.

Measuring map bearings with a British-style military lensatic compass

For many years, the British military have used possibly the most beautiful, heaviest, exquisitely accurate, and over-engineered field compass ever made. This design has been used around the world by armies of many nations, but it isn’t used so much these days. The standard NATO issue is now a plastic baseplate compass.

If you’re insane enough lucky enough to own one of these, such as my Francis Barker M-73 compass, you might want to know how to take a map bearing with it.

military lensatic compass being used for taking map bearings

Photo: Mark Beresford

There’s no straight edge on these compasses, so at first it looks impossible to measure a map bearing with one. However, if you open the lid you can see that there’s a notch at the top and a lubber line etched into the glass. The thumb ring at the opposite end has a tiny white mark, which you can just see in the photograph, and this aligns with the marks on the lid. You can therefore lay the compass on top of a line and follow the same method given for the USGI military lensatic compass.

In a pinch, this method works for both styles of lensatic compass, but just as strawberries go with cream, these beasts are meant to be partnered with a military protractor. Use a protractor to take very accurate map bearings and the compass to take very accurate field bearings.

Measuring map bearings with a baseplate compass

The baseplate compass is the most commonly used style of compass for hiking, and for good reason. It’s relatively cheap, lightweight, reasonably durable, can be used to measure bearings on a map and in the field, and slides easily into a pocket. Some models have additional features, such as the ability to correct for declination (magnetic variation), a magnifying glass, and luminous points.

When you use a baseplate compass for measuring a map bearing, the compass needle is irrelevant. Many people don’t get this. You’re simply using the rectangular base and the circular housing together as a protractor. You could remove the needle and still use the compass for this purpose. You don’t need to do any “red in the shed” business when measuring a map bearing.

To drive this home, take your baseplate compass and rotate the dial so that 0 degrees aligns with the top mark on the compass. Rotate the dial clockwise until it reads 45 degrees at the top mark. Now, look at the angle between the straight edge and the parallel lines printed on the bottom of the housing. The two make a 45 degree angle. Play around with it a little more until you get the idea that, for this purpose, the compass is just a protractor that measures angles.

Here’s how you measure the bearing:

  1. If the two points that you want to travel between are further apart than the length of the long edge of the baseplate, draw a line between them. In my example the two points are A and B.
  2. Rotate the map so that the north edge is pointing away from you (and the text labels used for the geographical features are the right way up)
  3. Place one of the long edges of the compass on the A-B bearing line so that the top end of the compass (with the arrowhead) points in the direction of travel.
  4. baseplate protractor being used to take map bearings

    Photo: Mark Beresford

  5. Rotate the housing until the parallel lines printed on the bottom (orienting lines) line up with the north-south reference direction that you’re using (the vertical graph lines in this case), and the red end of the orienting lines are facing the north edge of the map. This aligns the north end of the reference direction with the 0 degrees mark on the protractor. If it helps, you can slide the baseplate along the bearing line until one of the orienting lines exactly overlays the reference line.
  6. baseplate protractor being used to take map bearings

    Photo: Mark Beresford

  7. Read the bearing from the degrees scale at the main mark at the top of the compass.
  8. baseplate protractor being used to take map bearings

    Photo: Mark Beresford

Measuring map bearings with a smartphone compass app

For better or worse, some people are now navigating with electronic compasses found on smartphones, tablets, GPS receivers, and watches. Can you measure a map bearing with one of these?

The answer is yes, as this example for a smartphone shows. As a smartphone has no plastic housing with a degrees scale that you can manually turn, these devices mimic card-style compasses like the military lensatic.

Photo: Mark Beresford

Photo: Mark Beresford

Knowing this, you can now follow the same steps used for the USGI military lensatic compass to measure a map bearing with your phone.

So that’s it

To thoroughly learn how compasses work, try to use as many types as you can, and practice often. And as a final reminder, don’t forget to always state which reference direction you’re using for your bearing: grid, true, or magnetic.

If you’re looking for a way to protect your compass on the trail, you might be interested in How to make duct tape zipper bags for your gear.

For more terrific articles about navigation, see:

Have fun out there!

author in the place used to take map bearings

Photo: Mark Beresford

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Photo credits: Mark Beresford

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  1. Patrick Barclay says:
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    This article is interesting and educational. Count me in.