How to Use a Compass: The Ultimate Guide to Navigation

Every outdoorsperson should know the nuts-and-bolts of the compass. We live in an age when digital navigational tools abound: GPS receivers, satellite messengers, smartphone maps, and apps.

These are all well and good, wonderful resources to have—but they aren’t foolproof, and overreliance on them without backbone knowledge in tried-and-true map-and-compass wayfinding can leave us in dire straits. 

In this article, we’ll introduce the basics of how to use a compass: what the tool does, how it’s put together, and all the invaluable locational and route-finding information it can provide out there in the backcountry.

Why Should I Learn to Use a Compass?

A compass always has your back, keeping you from going in the wrong direction when navigating through remote wilds. Your smartphone might die, your GPS unit may act up, but that compass of yours—as long as you keep the magnetic needle away from interfering metal—points north through thick and thin. You can walk a straight course and stay oriented even when socked in by a cloud (or caught by darkness).

Now, even as we underscore the tremendous power of a compass, it’s worth noting there’s a surprising amount of sturdy wilderness navigation you can do without one. In many landscapes, experienced outdoorspeople can stay oriented just by matching obvious physical landmarks with their mapped locations.

Using such on-the-ground navigational aids as handrails (long linear features such as rivers, roads, or powerline corridors roughly aligned with your desired course of travel) and catchpoints (mapped landmarks along a handrail that peg your location), you can cover a lot of ground without peeking at your compass. 

But the point is, you should have a compass to peek at it if you need it—and, in many situations, using a compass and map together is the surest way to stay on track and avoid getting dangerously turned around. 

Introducing the Tool: Parts of a Compass

A magnetic compass consists of a freely rotating magnetized needle that lines up with the Earth’s magnetic field, one end of it usually a red arrow pointing north. (We’ll get into just what “north” means in this context shortly.) The needle does its thing within the compass housing, filled with a liquid that dampens the compass needle’s otherwise jittery movement. 

Along the rim of the housing or case, the 360 degrees describing a circle come hatched and labeled on a dial (aka azimuth ring or bezel ring). The four cardinal points (cardinal directions)—North, South, East, and West—are labeled at 360 degrees (or 0 degrees), 180 degrees, 90 degrees, and 270 degrees, respectively.

Some compass models denote not only the cardinal points but also the intercardinal points of North East, South East, North West, and South West, and occasionally even finer-scale divisions (North-Northeast, South-Southwest, and other secondary intercardinal points). 

Different Types of Compass

The cheapest compasses are fixed-dial models, but, while better than nothing, these aren’t the go-to choice for a dyed-in-the-wool hiker, backpacker, climber, or hunter.

That would be the baseplate compass, also known as the protractor compass given it serves as that tool in mapwork, or as an orienteering compass due to its original invention for use in that sport.

It goes without saying that the same skills competitive orienteer employs are part of a backcountry traveler’s basic route-finding toolkit. 

Baseplate Compasses

Baseplate compasses consist of a rotating bezel-set atop a see-through, square-edged base plate. Within the compass case, below that free-swinging compass needle, parallel lines known as meridian or orienting lines can be used to match with the north-south grid lines of a topo map.

At the center of the case and aligned with those meridian lines, an orienting arrow points to north on the compass housing.

The base plate will also typically include a direction-of-travel line or direction-of-travel arrow pointing toward the front edge of the compass. Its back end meets the rotating bezel at an index line. Two or three of the base-plate edges include multiple ruler measurements and scales for determining distances on a map.

Many orienteering compasses include a hinged cover with a sighting mirror. Run through with a line, this design allows you to hold the compass at eye level when pointing toward a target landmark or along a desired bearing, using the mirror (set at about a 45-degree angle) to confirm the direction where the index line meets the dial.

Other Types of Compasses

Now, keep in mind there are a number of other kinds of compasses: the stripped-down thumb compass, non-magnetic compasses such as the gyrocompass, the military-style lensatic compass or magnetic-card compass, digital compasses, and more.

But, given considerations of accuracy, ease-of-use, affordability, and general wilderness suitability, your average outdoor user is going to want to obtain—and, naturally, eventually master—a baseplate model.

For that reason, the rest of this article focuses specifically on baseplate-compass basics.

Understanding & Accounting For Magnetic Declination

Accurately using a compass and a topo map together in most parts of the world necessitates a bit of translation, you might say. The reason is that the two navigational tools actually have their own, different definitions of “north”: Your compass points to a different reference point than your map.

Declination: True North & Magnetic North

The north marker on your topo map refers to true north, aka “geographic north.” True north indicates the North Pole, the ultimate northern reference point we all tend to envision. But the arrow of your compass’s magnetized needle points to a different north: magnetic north.

Compared with stolid, unchanging true north, magnetic north describes a transient location: the northern tip of the Earth’s magnetic field—the so-called “magnetic North Pole”—which actually moves around due to the molten messiness of Earth’s deep innards.

So there are two complications we face when trying to use our compass with our topo map to find our way.

The first is the fact that magnetic north and true north differ. Magnetic declination describes the difference between true north and magnetic north in cardinal degrees. That difference is negligible along what’s called the line of zero declination, where true and magnetic north agree.

But off that line, you need to correct for a west or east declination in order to have your compass needle and map sync with one another. Without proper declination adjustment, your bearings translated between compass and map will be off, which can result in trekking majorly astray.

The other complication is the magnetic north’s roving ways. Many topo maps will indicate their depicted area’s declination via a diagram at the bottom, but this measure changes year by year; that becomes an issue after a while. This speaks to the value of checking your map’s revision date and going with as current an issue as you can.

But thanks to online resources such as the U.S. National Oceanic and Atmospheric Administration’s declination calculator or the Canadian Geomagnetic Reference Field, you can assure yourself of a thoroughly up-to-date declination adjustment.

Correcting for Declination

Many baseplate compasses offer built-in adjustable declination, achieved with the turn of a screw or some other mechanism. You can also use tape to identify your area’s declination correction or simply go through the math (subtracting or adding degrees per the given declination) when making measurements with a map and compass.

You can also correct for declination on the map rather than the compass by drawing in the appropriately offset lines, but that’s more troublesome; just pay the marginal amount more for a compass with adjustable declination.

If you’re planning a hiking trip in a different geographic region than where you usually go backpacking, remember to check the area’s declination and adjust your compass accordingly before hitting the trail.

All of what follows assumes you’ve corrected for declination on your compass.

How to Use a Compass to Take Bearings

A bearing describes the direction between two points as defined by the angle made by a line run through both locations and a given baseline, which in orienteering work is either magnetic or true north.

You can use a compass to take bearings from the landscape—considering your current position against a visible landmark—or from the map, measuring the angle between two mapped points. 

Direct Bearings

Take a direct bearing from a landmark you can see—a mountain peak, a lake, a grand old tree—by holding your compass level at your chest or (with a sighting mirror) in front of your eyes and pointing the direction-of-travel arrow at the feature.

Then rotate the compass housing until the compass needle’s contained within the orienting arrow, and read the measurement where the direction-of-travel arrow meets th