Compass Navigation 101: 4-Digit Grid – Survival Prepper

Compass Navigation 101: 4-Digit Grid

The compass is the ultimate tool when it comes to navigation. We don’t care about GPS, Google Maps, or any of that stuff that will fail the minute SHTF. When it comes down to the skills that separate the best preppers from the rest, it is their ability to effectively navigate using only a map and a compass.

In order to complete all of the lessons, you are going to need three pieces of equipment. While they can often be found at surplus stores, these are all pretty easy to find online.

Azimuthal Compass

Though this is the most important item, it will actually take a few lessons before you can use it. Do not settle for a cheap $10 POS that they sell at bargain stores. Invest at least $50-$100 for a military grade compass because they will last far longer, be more accurate, and have features (degrees, mills, distance rulers) that are essential to using a military map.

Military Grid Reference System (MGRS) Topographic Map

MyTopo is a website that can print custom MGRS maps for your specific area. Since they offer full customization you can add in overlays, additional information, and adjust the scale to whatever best fits your purposes. It should be noted that a bigger is not always better. Make sure that your map has the same scale as your protractor otherwise, they will both be essentially useless.

1:50,000 Scale Protractor

Most military protractors have three separate triangles for varying map scales, though the standard is 1:50,000. This isn’t the math tool used to map circles, so if you haven’t seen one before, search for one on Google. Remember it is imperative that you get a protractor with the same scale as your map.

The only other thing you need are some pencils (preferably mechanical) and some paper. In order to complete the lesson in this post, you will only need to have an MGRS Topographic Map.

The entire process of navigating with a compass is not hard, but it is extensive. In order dig into each step with as much depth as possible, we are only going to focus on plotting a point on your topographical map.

4 Digit Grid

First, it is imperative that you use an MGRS map and not one that only uses latitude and longitude lines. The MGRS overlay is much simpler and far easier to use with nothing other than a pencil and some paper. Though a compass is the key element to actually navigate, it will not be necessary for the rest of this post as it focuses more on the prep work rather than the navigation itself.

Once you have your supplies, then it is time to become acquainted with the map itself. Survey the map in order to get a feel for the symbols, legend, and grid identifier. The grid identifier is a set of letters that denote the specific 100,000-meter area in which the map covers. Some maps cover the boundaries between grid identifiers so make sure that your letters are specific for the appropriate grid. The letters should look something like AB, GS, or some other combination. This is only important if you plan on sharing your grids with another person as it doesn’t affect the use of the compass.

If you are able to plot points by using an intersection in the road or a water tower, you will save far more time than having to manually create them yourself. Find something prominent, for this example let’s say that you find a church that you want to use as your starting point. Normally, you would not need to find its grid, unless you were trying to walk to it with a compass. As long as you can get to the church on your own you will not need to do the next step.

Find the major grid lines that run across the bottom of your map. It is important to start from the bottom left corner as that is how maps are read. Find the closest vertical line that does not go past your point and write down the numbers. For our imaginary example it will look like:

AB 12– —-

Next, you will need to go repeat the same process, but instead of starting at the bottom left-hand corner and heading right, you are going to follow the horizontal grid lines that go up. Find the closest line to your point that does not go over it. Think of blackjack; if you go over, you bust. Take those numbers and write them into the fourth and fifth places of your grid outline. It should look like this:

AB 12– 56–

This is the simplest form of a military grid possible. While this is not useful for finding a specific area, it can be used to describe a general vicinity. By only using these numbers, you are going to get someone within one kilometer of the point that you had selected. The only time a four digit grid should be used is when you want to designate an entire area.

The next lesson will involve plotting the rest of the eight digits, so if you do not have a protractor make sure to get one. In order to practice, find some more prominent landmarks and find their four digit grid until you could do it in your sleep. Sign up for the email list if you want to be notified when Compass Navigation 102: Protractors is published.


My name is Steven Capps, and I have a B.A. in English from the American Military University. My writing has been featured in Fiction, The Bird & Dog, Survival Sullivan, The Cass County Star Gazette, and many others. I currently serve as an Infantry Sergeant in the U.S. Army National Guard.