How to Read a Compass (The Definitive Guide 2021)

In this article, I will show you exactly how to read a compass, step-by-step.

A compass is a necessary tool for survival in the wild. Knowing how to use a compass, in addition to a high-quality topographical map of the region you’re navigating, should guarantee that you never get lost.

In a few easy steps, you can learn to recognize the basic components of the compass, take a reliable reading of your bearings, and begin learning the required navigation skills.

Let’s get started.

General Directions

general compass directions

Firstly, a compass has four cardinal points: North, South, East, and West. When reading a compass and giving instructions to others, you can exclude the words “right” and “left” from your vocabulary.

Right and left are relative directions that change based on where you are and which way you are looking, but the cardinal points remain unchanged.

NorthEast corresponds to the direction halfway between North and East, which is an intercardinal point. SouthEast, SouthWest, and NorthWest are the remaining three intercardinal points.

Finally, secondary intercardinal points are located halfway between each cardinal and intercardinal point—North-NorthEast, East-NorthEast, East-SouthEast, South-SouthEast, and so on.

With these instructions, you will give someone a clear idea of where they need to go. We might add further points by cutting each segment in half again and again but asking someone to go East-EastEastNorthEast-EastNorthEast-EastNorthEast-EastNorthEast-EastNorthEast-EastNorthEast-EastNorthEast, which is super exact.

Types of Compasses

We’ll talk about the mountaineering compass, also known as the orienteering compass. This is the sort with a needle that always points North and allows you to turn a dial to get directions.

You’ve also seen car compasses or toy compasses, all of which lack a discernible needle and are referred to as “Card Compasses.” Really, there is a magnetic piece similar to a needle, but it is glued to a paper disk (card) or has a plastic ball around it that is free to spin.

The card (or ball) stays set as the vehicle rotates, so the portion you see shifts. These are good for general instructions, but they aren’t useful for what we’re looking for.

Parts of Your Compass

Compass parts

A compass can be used for various purposes, from determining which direction is North to discovering buried treasure to taking an unmarked route across wilderness terrain. But you have to start small, so let’s look at what parts there are in a compass:

Not all compasses have all of these pieces, and some have even more.
BaseplateA hard, flat surface to which the rest of the compass is attached. It has rulers on the edges to help you calculate distances on maps. It has a straight edge that is useful for drawing lines on a map.
ScalesEach compass edge can have a separate ruler for use for different map scales.
Direction-of-Travel ArrowThis is on the baseplate. You point this in the direction you want to go.
MagnifierGreater visibility of small map features
Index PointerThe pointer indicates the butt end of the direction-of-travel arrow. It comes to an end right at the edge of the dial, where you take degree measurements.
DialA ring that wraps around the housing and has degree markings engraved on it. To rotate the entire housing, you grip the dial and rotate it.
Declination MarksUsed to orient the compass in a region with a known declination.
Orienting ArrowMarked on the housing’s surface. When the knob is rotated, it rotates with the housing. It is used to coordinate a compass with a globe.
Orienting LinesA series of parallel lines are outlined on the housing’s floor and the base plate.
NeedleA magnetized metal piece with one end painted red to signify North. When the compass is kept equally straight and stable, it rests on a fine point that is almost frictionless, allowing it to spin freely.
HousingThe key portion of the compass is located here. It is a circular plastic jar filled with liquid that houses the compass needle.
BubbleA bubble of air in the housing liquid is useful for ensuring that the compass is kept equally straight.
MirrorAllows you to see the compass face as well as distant points at the same time. This is useful for emergency signaling.
SightIncreases your ability to point your compass at distant objects.

Steps to Read a Compass

1. Adjust Declination

This video is a great source if you want a general, visual overview of declination adjustment.

To begin, what is declination, and why is it important? The angular distance of a point North or South of the equator is defined as declination.

A magnetic compass needle will align with the local magnetic field, which is not quite the same as true North. Correcting for this disparity, known as declination, is essential to have while using a magnetic compass. 

The amount of declination depends depending on where you live. 

The green line on the US/UK World Magnetic Model map shows the only place where the local magnetic field aligns with the true North. If you happen to be on one of the green lines, your declination is zero(0), which means no correction is required.

The rest of us, on the other hand, would have to fix it. The Canadian Arctic is magnetic North. As a consequence, in the western United States, a magnetic compass would point too far east. A magnetic compass would point too far west in the eastern United States. 

Topographic maps usually have declination values for a given region. San Francisco already has a declination value of around 14 degrees east. The current declination of New York City is around 13 degrees west. What is the most recent? Is it evolving? 

Unfortunately, the answer is yes. Just not straight away. So, as long as your topographical map is not too old, you should be perfect. A good guide for evaluating the declination is:

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https://www.ngdc.noaa.gov/geomag-web/#declination

So, to correct declination, first assess the physical offset. You should look up the current declination and set your compass if your compass has a declination change (it may be a screw or dial setting). 

The declination setting actually offsets the compass orienting arrow from the rest of the compass dial by the required number of degrees. The declination correction in this first example is set to 15 degrees east. 

To put it another way, the orienting arrow is 15 degrees to the right of the cardinal point North. In the following case, the declination correction is set to 15 degrees west. To put it another way, the orienting arrow points 15 degrees to the left of the cardinal point North.

If you’ve manually changed the compass, each time you line up the needle with the orienting arrow, the exact degrees, and cardinal points will be corrected for your position.

2. Declination Alternative (Doing the Math)

If the compass lacks a declination correction, the orienting arrow will still point to the letter “N” on the compass dial. In fact, the orienting arrow might also have the letters “MN” written on it, suggesting that it is only for magnetic North.
 
To make the requisite corrections, you must manually add or deduct the declination value. While the magnetic needle seems to be pointed North, it is actually pointing south due to declination.
 

Using the previous examples, if you are in an area with a 15 degree west declination (say, somewhere on the East Coast of the United States), the needle is pointed to 15 degrees west of true North. To correct, you need to move back 15 degrees towards the east.  

To find true North, you need to add 15 degrees.  Since North is zero(0) degrees, true North would be what appears on this compass as 15 degrees (halfway between 0 and 30 degrees).

 

However, if you are in an area with a 15-degree east declination (say, somewhere on the West Coast of the United States), the needle would be pointed 15 degrees east of the true North. You must shift 15 degrees to the west to the right.

Subtract 15 degrees from the true North to find it. North may be thought of as zero(0) or 360 degrees since a compass represents 360 degrees. By subtracting 15 degrees from 360 degrees, you will determine the true North is 345 degrees on this compass (halfway between 360 and 330).

3. Orient Your Map

Here is a nice video to show you how to orient your map, if your map is old.

The method of accurately aligning a map relative to its surroundings is known as orient. In other words, a centered can have the top of the map pointing true North and the bottom pointing east. 

To orient, a map with a compass, first aligns the compass dial with the direction of travel. Ignoring the magnetic needle’s path, for the time being, position the compass on the map’s surface such that the direction of movement points to the top of the map. 

In other words, the “N” symbol on the compass corresponds to the map’s North indicator.

Slowly pivot the whole body when keeping the map and compass together before the compass needle and the orienting arrow are matched.

If all went well, the compass needle should still be aligned with the orienting arrow, and the N on the compass dial should always be aligned with the North on the map. The map is properly oriented when all of these conditions are met. 

Remember that if your compass does not automatically compensate for declination, you must do so manually. Some people do this by aligning the compass with the magnetic North symbol on the map rather than the true North.

4. Take a Bearing

A “bearing” is just a more detailed way of defining a direction in navigation. For example, instead of going “northwest,” you might follow a bearing of 315 degrees to get to a campsite.

Bearings are often measured with a given position. Following the same bearing from two different locations would not result in the same destination.

When you know where you are on a map, you can use a bearing to get to a location:
  1. Set the compass on the globe so that the baseplate’s straight side meets up with your current position (1a) and the map location for a target, such as a campsite (1b).
  2. Check that the travel arrow is pointed in the general direction of the campsite (it should not be upside down).
  3. Rotate the bezel, so the compass’s orienting lines coordinate with the North-South grid lines and/or the map’s left and right sides. (Ensure the North marker on the bezel is pointing North, not south, on the map.)
  4. Examine the index line to assess the bearing you’ve just caught.
You can now use the compass to navigate to your destination: 
  1. Hold the compass such that the travel arrow points away from you.
  2. Rotate the body until the magnetized needle is positioned inside the orienting arrow. The trajectory of the travel arrow is now facing the bearing you captured, and you can trace it to your destination.

A bearing can also be used to position yourself on a map. You may want to know where you are in relation to a trial.

  1. Begin by locating a landmark that you can also locate on your map.
  2. Maintain the compass flat, with the travel arrow, pointed away from you and straight at the landmark.
  3. Rotate the bezel before the magnetized needle is centered inside the orienting arrow.
  4. Examine the index line to assess the bearing you’ve just caught.

You can now use the bearing to locate your position on a map:

5. Put the compass on the map and align one of the straight edge’s corners with the landmark.

6. Rotate the entire baseplate until the orienting lines are running North/South (6b) and the North marker on the bezel is pointing to North on the map, thus maintaining that the direction of the travel arrow stays pointed in the general direction of the landmark (6a) (6c).

7. Draw a line on the map around the straight side of the compass now (7a). Your place is where the line from the landmark crosses your trail (7b).

5. Triangulate Compass

You may also use several bearings to locate yourself on a map. If you are not on a linear function, such as a trail, you can still locate your position on a map. 

This method, known as “triangulation,” allows you to repeat these steps for a second and third landmark, preferably ones that are at least 60 degrees apart from the first (and each other). 

If the lines you draw intersect at a single spot, you’ve found your place. However, much of the time, the three lines will form a small triangle—your position will be in or near that small area. Recheck your job if the lines form a huge triangle because you have at least one major mistake.

Compass Reading Tips

  1. Keep the compass flat – if the compass is not flat, the needle will hit the transparent lid and will not adjust properly.
  2. Read the right end of the needle, the red one.
  3. Using common sense, such as understanding that if you’re in North America, Europe, or Asia and going for the sun in the middle of the day, you’re heading south. If you are south of the equator and heading towards the sun, the reverse is true, and you are heading North. (This tip should not be used while you are in the tropics, between the Tropic of Cancer at 23.5 degrees North of the equator and the Tropic of Capricorn at 23.5 degrees south of the equator. Depending on the time of year, the sun will be either North or South of you.)
  4. Keep metal items away from the compass; even a knife, flashlight, or keychain will trigger a false reading if placed too close to the compass.
  5. Keep the compass up to your eye and look down the travel arrow path to locate landmarks, reference points, and so on.
  6. Trust your compass: it will point you in the right direction 99.9% of the time. Many landscapes mimic one another, but once again, TRUST YOUR COMPASS.

How to Read a Compass FAQ

How to read a compass app on the iPhone?

The iPhone Compass app isn’t as precise as a real compass, but it’ll help you follow simple directions and bearings in a pinch.

  1. From your Home screen, open the Compass window.
  2. Place your iPhone face down in the palm of your hand.
  3. Spin your iPhone around until you reach the bearing (degrees) you intend to pursue. 30 degrees North-Northeast, for example.
  4. Tap the compass face once to secure the bearing.
  5. To lock in the bearing, tap the compass face once.
  6. From your home screen, go to Settings.
  7. Tap Compass.
  8. Select Use True North by clicking the switch next to it.
  9. From your Home screen, open the Compass app.
  10. Swipe to the left on the compass face. If you keep your iPhone flat in your hand, you can see white bubbles encircling a black number, the horizontal stage. The vertical degree is obtained by tilting your phone so that the screen is parallel to your face.
  11. Place your iPhone flat on the top of the item to be leveled. 
  12. Tilt your iPhone in all directions before the screen turns green and you reach 0 degrees.
  13. You can turn the black screen red by tapping once, and it will remain that way until your iPhone is level, at which point it will turn orange. 
  14. Place your iPhone against the item you’re attempting to vertically level. 
  15. Tilt your iPhone in both directions until the bottom half of the screen turns green and you cross 0 degrees. 
  16. Tap the degree once more if you want to take another calculation based on the angle. When you move away from the angle you were on, you’ll see red. This can assist you with measuring 90-degree and 45-degree angles.
Here is a decent video covering some important things I discussed:

Which Arrow Should I be looking at on a Compass?

It’s the one in red. The red (magnetic) needle may contain a small “N” letter, which denotes North.

How do I know which direction the wind is coming from?

Turn around so that the breeze is in your ears. Use your compass to determine which direction you are looking. The wind is blowing from that direction.

Final Thoughts

Now, you know exactly how to use a compass the proper way! Don’t be afraid to re-read this article for full comprehension.

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