What is MOA? Understanding and using Minute of Angle

What is MOA?

MOA stands for Minute of Angle.

Let’s break this term down…

“Minute” is a way to refer to 1/60th of something. For example, 1 minute of an hour is 1/60th of that hour. Therefore, we now know that 1 MOA is one sixtieth of an angle…but which angle is MOA referring to?

The “Angle” in MOA (Minute of Angle) is one of the 360 degrees in a circle.

Therefore, MOA is 1/60th of one degree in a circle.

Source: MOA vs Mil article I wrote for RECOIL magazine

You may now be asking: “Why is MOA used with rifle scopes and long range shooting?”

Great question! However, before we get into why (and how) MOA is used for shooting rifles,  First we need to understand a bit more about what Minute of Angle is.

The first thing to understand about Minute of Angle (MOA) is that it is an angular and not a linear measurement.

What does that mean?

It means that a Minute of Angle is just like any other angular measurement… it can only refer the the angle between two things and NOT a length.

Here’s how I like to explain Minute of Angle (just like I do in the video below and the Long Range Shooting Handbook):

MInute of Angle Explained

Imagine holding two laser-pointers in your hand and pointing them at a target 100 yards away. Now, if you spread those two laser pointers apart at a certain angle, the lasers’ dots on the target will spread further apart.

If the laser-pointers were spread apart at a 45 degree angle, the dots would be very far apart at 100 yards. However, if the laser pointers were spread apart at a small angle, let’s say 1/60th of one degree (one MOA), then the laser pointers’ dots would be about 1 inch apart.

Pretty cool huh?

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Now, even though we just learned that 1 MOA is about 1 inch at 100 yards, it is NOT accurate to say “1 MOA is an inch.”

This is because MOA is an angular measurement and the liner distance (what we’re measuring in inches in this example) changes depending on how far away from the laser pointers we are.

Therefore, it is more accurate to say that 1 MOA is about 1 inch at 100 yards.

So, how big is 1 MOA at 200 yards?

1 MOA is about 2 inches at 200 yards.  Yep, it’s now a 2 inch liner measurement at 200 yards even though we’re still dealing with one MOA.

Go back to those laser pointers in our previous example.  If you moved the 100 yard target out of the way and let the lasers travel to a 200 yard target, they would continue spreading apart and they’d end up about 2 inches apart at the 200 yard target.

Source: MOA vs Mil article I wrote for RECOIL magazine

It is therefore fair to say that 1 MOA is about 1 inch per 100 yards.

One MOA is about 5 inches at 500 yards, about 10 inches at 1000 yards, and so on.

Because MOA is an angular measurement, you must know the distance before a linear measurement (size on a target) can be known/calculated.

What is MOA Exactly?

If you’ve been paying attention, you’ll notice that I used the term “about” when I explain that 1 MOA is about 1 inch per 100 yards.

Technically, 1 MOA is 1.047 inches per 100 yards.

However, I see no need to be that precise and instead round down and use about 1 inch at 100 yards.

Wait… did I just tell you to not worry about being precise when you’re trying to learn about precision shooting?

Yes! Let me explain:

At 1000 yards, a true MOA is 10.47 inches whereas my rounded MOA is 10 inches at 1000 yards.

I argue that the 0.47 inch difference in MOA calculations at 1000 yards is not enough to worry about. For one, the 0.47 inches is slightly wider than the width of the bullet you’re likely to be shooting at 1000 yards. Second, most shooters (me included) can not see a 0.47 inch adjustment at 1000 yards because we can’t shoot groups that small.

Also, it’s MUCH faster to work with the rounded MOA calculations. Yes, it’s not as precise, but the distance to the target may not be as precise as you’d like and most people can’t enjoy the benefit of the precise difference for 1 MOA.

For example, here’s a chart of MOA calculation comparison:

Of course, if you’re dealing with multiple MOA adjustments, then that 0.47 inch difference starts adding up. However, I don’t think this makes much of a practical difference because this would only matter if you were doing a calculation before ever shooting at a distance and wanting a perfect result.

For example, most shooters will try to shoot with an approximate elevation adjustment needed for their rifle and bullet. Then, they’ll fine-tune the adjustment as needed.

If, however, you wanted an exactly 450 inch adjustment at 1000 yards from your 100 yard zero, then you wouldn’t get it by adjusting up 45 MOA. Instead, you’d get a 471.15 inch adjustment.

Why does this not matter (or will it be unlikely to matter)? Most of the time, you won’t be trying to make a large adjustment of inches like this. Instead, you might find that you should adjust 45 MOA to hit at 1000 yards for your particular caliber.

Minute of Angle Explanation Video

If you like how I explain what MOA is, you really should check out this video of me explaining MOA that I filmed for the NSSF. We thought that it’d be a popular topic but we had no idea that a couple million people would watch it to learn about MOA.

In our video, we delve into how to use MOA. In this article, we start that topic below the video.

What is MOA: How to Use MInute of Angle

The biggest “aha” moment in the above video for many shooters is my advice to think in “chunks” of MOA at a certain distance BEFORE trying to calculate MOA adjustments.

The math for calculating MOA is very easy. In fact, it is so easy, that some rifle shooters get wrapped around the axle and get the wrong answer by trying to make MOA difficult.

Here’s my MOA trick:

Think in MOA chunks for the distance you are shooting.

As an example, let’s pretend that you are shooting at 400 yards. From the MOA explanation above, we know that 1 MOA will equal about 4 inches at 400 yards. Therefore, start thinking in “4 inch chunks” for our 400 yard target.

If your bullet is 4 inches low at 400 yards, you know that 1 of your “4 inch chunks” will fit into that 4 inch adjustment. Therefore, you’ll need to adjust up 1 MOA.

If however, your bullet is 8 inches low at 400 yards, then you should note that 2 of those “4 inch chunks” will fit within the 8 inch adjustment. Therefore, you would need to adjust up 2 MOA at that distance.

Now, it doesn’t need to be even numbers to work. For example, with this method, you should be able to easily see that 1.5 MOA is needed to adjust 6 inches at 400 yards because 1.5 of those “4 inch chunks” will fit within  the 6 inch difference.

What is MOA? It’s Not “Clicks”

Here’s some more advice: if you’re going to use MOA, then use MOA!  Stop talking in “clicks.”

First, by always talking about and referring to MOA, you will understand how to use it better. Of course, there’s always the option to use Mils.

Also, by using “clicks” you’re likely to confuse yourself when switching between rifles or for you and your shooting buddy to confuse each other.

If I tell you to adjust up 1 MOA, then it is up to you to know how many “clicks” on your scope is required to get that 1 MOA adjustment.

However, if your scope adjusts in 4 clicks per MOA and mine adjusts in 2 clicks per MOA, then me telling you to come up “2 clicks” (when I should have said 1 MOA) will result in you making the incorrect adjustment by 50%.

MInute of Angle Formulas

Yards to Target / 100 = inches per MOA adjustment at that distance

Inches of Adjustment Needed / Size of 1 MOA Chunk in Inches = MOA adjustment

Clicks per MOA on Scope x Number of MOA Adjustment Needed = Number of Clicks Needed for Adjustment

Note, if you want to use 1.047 inches per 100 yards instead of 1 inch per 100 yards, then multiply the (inches per MOA at that distance) by 1.047

What is MOA? Questions and Answers.

If you’d like some practice to ensure that you understand what MOA are, here you go!

If you’re looking for more discussion on this topic, and more questions and answers, please check out the Long Range Shooting Handbook.