True North vs. Magnetic North vs. Grid North
What’s the Difference Between True North, Magnetic North, and Grid North?
You’re in the right place! In this guide, we will be covering the following:
- A brief explainer on the meanings of True North, Magnetic North, and Grid North
- A comparison of each of the “Three Norths”
- A short guide on declination
If you’re an avid hiker, you have probably learned a thing or two about following maps, using a compass, or at least going in a generally accurate direction.
Even if you’re only an occasional hiker and tend to hit only well-marked trails, however, it can be beneficial to delve a little deeper into the specifics of backcountry navigation.
These days, we all have smartphones and even high-tech vehicles that can usually tell us precisely where we need to go. While super helpful, these devices are not foolproof. Batteries can die, cars can break down, and cell phone reception is usually absent in those places where you most need it.
In such situations, a little bit of “old-school” navigational knowledge can go a long way.
In this post, we aim to provide you with that knowledge. We’ll be looking at the differences between Truth North, Magnetic North, and Grid North, and explain how this can help you out in a bind.
The Three Different Norths
If you’ve never explored the world of maps and the technical jargon that comes with the territory, you could be forgiven for being a little bit confused.
“How can there be three different norths? Isn’t north just north?” You might ask.
The short answer to this question is no. There are three different “norths” that cartographers (and outdoors enthusiasts) have to consider. These are True North, Magnetic North, and Grid North. While they all sound like the same thing, each is unique in its own way. The only way to know the difference is to define them.
True North is another way of referring to geographic or geodetic north. Geographic North is represented by something that should sound familiar to you: the North Pole.
The Earth is mapped out using a series of imaginary lines called longitude and latitude. The former of these, longitude, run vertically around the planet from the very north (the North Pole) to the very south (the South Pole).
True North is the point where these invisible lines all meet at the northernmost point of the planet.
If the exact location of the northernmost point of the lines of longitude is True North, then what is the difference between Magnetic and True North?
True North vs. Magnetic North is where things start to get slightly more complicated.
Rather than sitting in the same location as True North, Magnetic North typically rests somewhere in Northern Canada. The easiest way to explain Magnetic North is to start out with the idea that the Earth serves as—in non-technical parlance—one humungous magnet.
Because the Earth functions as a magnet we can use a compass (which uses a magnetized needle) to determine our location and point us in the right direction. Magnetic North will be where that magnetized needle points to when you hold it in front of you.
The exact location of this point is actually always shifting over time. In fact, some of the most recent readings of Magnetic North have found it shifting out of Canada towards Siberia. The availability of technology and specific data has allowed scientists to track the ever-changing location of Magnetic North and even to predict future migrations.
So, what does this mean for hikers?
Firstly, because we take readings from our map and compass based on True North, it’s vitally important that we remember that our compass will only point towards Magnetic North (not True North) and to adjust our readings for magnetic declination (more on that below.)
Secondly, because Magnetic North is always shifting, always be sure to check the declination for the area in which you’ll be hiking before hitting the trail.
Finally, what is Grid North?
Both True North and Magnetic North refer to a specific location or point. Grid North, however, refers to the northward direction identified by the gridlines of a map.
But why do these differ from True North?
Well, because your map is flat and the Earth is round, a slight variation is required to compensate for the curvature of the Earth. This variation is so slight, in fact, that most land-based navigators (i.e. hikers, backpackers, and cyclists) can safely ignore the difference without worrying about veering off course.
A Complex Relationship
Navigation professionals and cartographers alike use all three of the norths to understand topography.
But should all this matter to you and me?
The answer lies in something called declination.
Because True North and Grid North only vary by the smallest of margins, the relationship between the two won’t significantly affect your readings in the field.
However, the same cannot be said of the difference between True North and Magnetic North, where we have to account for the issue of declination.
Declination is, in simple terms, the difference that exists between True North and Magnetic North.
And here lies the problem…
Maps are designed to reflect how terrain relates to True North and our compass’s magnetized needle points towards Magnetic North. Because of this, we have to adjust our compass for declination in order to take accurate readings and navigate effectively.
But is it really necessary?
In short…yes! A 2 or 3-degree declination might not make much difference over a few hundred yards, but over a mile or two it could land you well wide of your intended target. And if that figure happens to be in the double figures, you could well find yourself a mile or more astray at the end of a day’s walking.
To find out the declination value for your area, you can use one of many online declination calculators. All you have to do is enter your location and the date, and the calculator will do the rest.
Some topo maps, handily, also list declination in the area they cover based on the year that the map was published. This is typically printed on the cover or in the legend (the box containing a table of symbols printed on the map).
Whether you’re an all-out adventurer, an occasional camper, or just an enthusiastic learner, learning the difference between True North, Magnetic North, and Grid North can be an eye-opening experience.
We hope the above article has also shown, however, that adding this knowledge to your outdoor smarts is vitally important to navigating safely and efficiently in the wild. When those batteries die and you need to navigate the old-fashioned way, it will serve you well…
If you have any thoughts or comments on this topic, we would love to hear them! Please feel free to post them in the comments section below!