How to Take a Back Bearing

Learning how to take a back bearing is a simple navigation skill that can give you a useful check on where you have come from. It is particularly helpful when you’re navigating across open ground, checking a route or trying to confirm that a feature you’ve identified is actually where you think it is.

Once you understand the basic idea, taking a back bearing is straightforward. The important part is knowing which direction you want to measure and remembering how to reverse the bearing correctly.

What Is a Back Bearing?

A back bearing is the direction back to where you have just come from.

For example, imagine you have walked from point A to point B on a bearing of 070°. If you stop at point B and take a back bearing, the direction back towards point A is 250°.

The two bearings are exactly 180° apart.

This gives you a useful way of checking your direction of travel. If your original bearing was 070°, the back bearing should be 250°. If it isn’t, something has gone wrong with your calculation or the way you are holding the compass.

Remember the 180° Rule

The easiest way to calculate a back bearing is to add or subtract 180°.

If your original bearing is less than 180°, add 180°.

For example:

070° + 180° = 250°

If your original bearing is 180° or more, subtract 180°.

For example:

250° − 180° = 070°

A few more examples:

Original bearing	Back bearing
045°	225°
090°	270°
120°	300°
180°	000°
225°	045°
300°	120°
350°	170°

The important thing is that bearings always run from 000° to 359°. If your calculation reaches 360° or more, work back around from 000°.

Take a Bearing Before You Set Off

One of the easiest ways to use a back bearing is to take your original bearing before you start walking.

Suppose you’re standing at one point and need to walk towards a distant feature. You take a bearing of 120° and start walking.

Make a note of that bearing.

When you reach your destination, the back bearing should be 300°. If you later need to return to your starting point, that gives you a useful reference for the direction you need to travel.

You should still use your map and other navigation information, but the back bearing gives you another check.

How to Take a Back Bearing With a Compass

If you want to take a back bearing directly rather than calculating it from your original bearing, stand where you are and identify the point you want to take the bearing towards.

Hold the compass level and point the direction-of-travel arrow towards that point.

Then rotate the compass housing until the red end of the magnetic needle lines up with the orienting arrow, as you would when taking a normal bearing.

Read the bearing from the index line.

That reading is the direction from your current position towards the point you are looking at.

If you are specifically trying to check the direction back to where you came from, make sure you are actually sighting on your previous position or a recognisable feature associated with it.

Use a Recognisable Feature

You don’t necessarily need to see the exact point you started from.

A prominent hill, building, tree, radio mast or other identifiable feature can be used as a reference.

For example, if you walked away from a distinctive hill on a bearing of 110°, you would expect the reverse direction to be 290°. If you can identify that hill behind you, you can check whether it lies roughly in that direction.

This is particularly useful when you’re learning because it lets you compare what the compass is telling you with something you can actually see.

Use Back Bearings to Check Your Navigation

A back bearing is useful because it gives you another way to test whether your navigation makes sense.

Imagine you’ve been walking for some time and think you’ve reached the correct point. You identify a feature behind you and take a bearing towards it.

If the bearing doesn’t make sense compared with your route, don’t simply ignore it.

Stop and work out why.

Perhaps you took a wrong turn. Perhaps the feature you identified isn’t the one you thought it was. Or perhaps you’ve simply made a mistake with the compass.

Finding the disagreement while you’re still able to work out where you went wrong is much better than carrying on and hoping it sorts itself out.

Back Bearings Are Useful in Poor Visibility

A back bearing can be particularly useful when navigating in poor visibility.

In fog, heavy rain or darkness, you may not be able to see very far ahead. Having a bearing for the direction you’ve just travelled can help you maintain a sense of where you’ve come from.

However, don’t rely on a single bearing as your entire navigation plan. In poor visibility, careful route planning, map work and regular position checks become even more important.

Be Careful With Your Compass

A back bearing is only useful if you’ve taken the original bearing correctly.

Keep the compass level when taking a reading and make sure the magnetic needle is free to move. Keep metal objects and electronic equipment away from the compass where practical, as they can affect the reading.

Don’t rush the process.

A few extra seconds checking your compass is much better than walking off on a bearing that you haven’t actually confirmed.

Don’t Confuse a Back Bearing With Looking Behind You

A back bearing isn’t simply the direction you happen to be facing when you turn around.

It is the bearing from your current position towards a specific point behind you.

That distinction matters.

If you’ve been walking on a winding path, for example, the direction you need to travel back along the route may not be the exact opposite of the direction you were facing at the last step.

The 180° calculation gives you the opposite bearing of the bearing you originally travelled on. If your route has changed direction since then, you need to take your current position and route into account.

Practise the 180° Calculation

You don’t need to be outdoors to practise this part.

Write down random bearings and calculate their back bearings.

Try:

035° → ?

145° → ?

210° → ?

315° → ?

The answers are:

035° → 215°

145° → 325°

210° → 030°

315° → 135°

Once the calculation becomes automatic, you won’t have to stop and think about it every time you need one.

Use Back Bearings as Part of Your Navigation

A back bearing isn’t a replacement for knowing where you are.

It is another piece of information that can help you check your route.

Use it alongside your map, compass, visible landmarks and other navigation clues. If several pieces of information agree, you can be much more confident that your route makes sense.

And if something doesn’t agree, that’s useful information too.

Stop, check your position and work out what has happened before continuing.

Make the 180° Rule Second Nature

The key thing to remember is simple:

Less than 180°? Add 180°.

180° or more? Subtract 180°.

That’s all you need to calculate the reverse of a bearing.

Practise it until you can do it without thinking, then start using back bearings during real navigation exercises. It is a small skill, but it can become a very useful part of checking your route and understanding where you’ve come from.