How to Adjust Your Compass Declination and Why it Matters

Knowing how to properly use a compass and finding your bearings should be one of the first skills you should consider learning before venturing out on your own into the Great Outdoors; a lot of travellers and hikers, however, use their compass the wrong way.

That’s because they fail to account for declination, a mistake that can potentially send you miles off from your intended destination and get lost.

What is declination, you ask?

Let us explain.

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Magnetic North vs True North

What we’ve all learned in school is that there are four fixed cardinal directions, north, east, south and west. You can use the arrow of your compass to identify north, establish the position of the other 3 cardinal directions and use these references to orient yourself during your hike.

The problem is, your compass is not exactly pointing north. Or at least, it is, just not the right one.

What your compass is indicating is what we call magnetic north, an ever changing direction that the needle shows as it is being pulled by the Earth’s powerful magnetic field. What you really need to orient yourself properly is true north, which is basically a straight line between you and the geographic North Pole.

The difference in degrees, along with the either west or east direction, between these two directions is called declination. It is essential to know for long distance hikers, since following magnetic north instead of true north over a long period of time will surely send you completely off track from where you intended to go. On the other hand, you probably won’t notice the difference on day hikes, since the gap increases gradually with distance.

To easily visualise the impact that not taking declination into account can have, draw a V on a piece of paper, imagining that one line indicates magnetic north true north and the other indicates true north. Keep extending the two lines, and you’ll see how fast the gap between them increases. Picture this on a map, and you can easily imagine how far off this can send you from your destination.

How to adjust the declination on your compass

Now that we’ve established the difference between true north and magnetic north, how do you take this into account when using your compass?

Adjusting the declination on a common basic orienteering compass is easy, but requires a few steps. The only things you’ll need are either a map or access to the internet, and an orienteering compass with a rotating bezel.

If you don’t already have one, we definitely recommend you check out the Suunto A-10 or the Silva Ranger 2.0, as both are amazing models for both beginners and experienced hikers!

Find the correct degree of declination

The degree of declination is dependant on the Earth’s magnetic field, and as such it is constantly shifting depending on the year and your position in the world.

Luckily, you can easily find this information online, such as on the NOAA official website, as well as any up to date topographical map. Remember though, the value of declination is constantly changing, so the map must be as recent as possible!

Adjust your bezel

Once you have established the value in degrees of the declination, you’re going to first make sure that the north indicator the bezel of your compass is facing the 360° mark. Then, while standing still, you’ll simply have to rotate your bezel by the number of degrees indicated by the declination value.

For example, if the declination is 15° West, you’ll rotate the bezel to the right until the indicator falls on the 345° mark. If it is, let’s say, 20° East, you’ll instead turn the bezel left to the 20° mark.

Adjust your position

After having adjusted your bezel, you’re going to slowly turn your body and compass until the magnetic needle is sitting in the middle of the printed orienteering arrow. You are now facing true north, and your compass is adjusted for declination!

Many high-end compasses, such as the Suunto MC-2, will have an addition screwdriver-like key that inserts in a small slot on the underside to allow you to set a semi-fixed declination.

This feature won’t matter much to you if you’re simply using your compass to determine your direction, but it is a huge help when used in conjunction with a topographical map for navigation. But this is another long and complicated topic that we’ll cover in another post.

Important terms

• Magnetic North

  The direction the needle of your compass naturally turns towards as it is being pulled by the Earth’s magnetic field.

• True North

  A straight line from your position towards the geographic North Pole, it’s the reference you need to establish the direction of all the other cardinal directions.

• Declination

  The difference in degrees east or west between magnetic north and true north. Used to adjust your compass to determine the direction of true north.

And there you have it, now you know how to set the declination on your compass!

Now you can hit the trail and make sure you’re actually headed in the direction you meant to, instead of going blind and getting yourself lost.

𝘿𝙞𝙙 𝙮𝙤𝙪 𝙚𝙣𝙟𝙤𝙮 𝙩𝙝𝙞𝙨 𝙖𝙧𝙩𝙞𝙘𝙡𝙚 ?

𝘠𝘰𝘶 𝘤𝘢𝘯 𝘴𝘢𝘷𝘦 𝘰𝘳 𝘱𝘪𝘯 𝘵𝘩𝘪𝘴 𝘪𝘮𝘢𝘨𝘦 𝘴𝘰 𝘵𝘩𝘢𝘵 𝘺𝘰𝘶 𝘤𝘢𝘯 𝘢𝘭𝘸𝘢𝘺𝘴 𝘭𝘰𝘰𝘬 𝘣𝘢𝘤𝘬 𝘰𝘯 𝘵𝘩𝘦𝘴𝘦 𝘵𝘪𝘱𝘴 !

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