Introduction
Some people call it weaponized math, which I like. But MOA is a shortened acronym used to describe a Minute Of Angle.
A minute of angle is an angular measurement similar to a degree. We know that there are 360 degrees in a circle, and we can use a compass to pan a certain amount of degrees right or left, just like when you learned orienteering in boy scouts as a kid.
A Minute Of Angle (MOA) is 1/60th of a degree, so it’s just a finer scale of measuring an angle offset. An MOA can be cut up into sixty seconds of angle, but that is getting so fine we probably don’t need to go into it.
As an angular measurement, shooters use the fine-scale to adjust their sights. In the same way pilots use degrees to adjust their flightpath, we use MOA to adjust the flight of our projectiles.
I’ve been playing in that realm for a few decades now, so I’ll do my best to explain this dangerous math as best I can.
What Does MOA Mean?
As I mentioned, MOA stands in for the mouthful; Minute Of Angle. There are several other ways that shooters measure shooting corrections and deviations, the more popular being MRAD (abbreviation for Milliradian) and IPHY (Inch Per Hundred Yards). But let’s not muddy the water and stick to our subject, MOA.
MOA and Target Distance
As an angular measurement, the size of a minute of angle gets bigger as it gets farther away from you.
Imagine it like a very long orange traffic cone. When you look through the hole at the small end, it may only be one inch in diameter. But the same cone at the big end, maybe ten or more inches wide, the angle of that increase IS an MOA.
So keeping with our example, if the small end of the cone was two inches in diameter, then to maintain the same angle at the other end, it would have to be twenty inches in diameter.
Back in the old days, before laser rangefinders, people with less hair than me would use these mathematical calculations to estimate distance. If you know an average male is about six feet tall, you can use an MOA scale built into your riflescope reticle to measure how many MOA tall he is and reverse the math to figure out roughly how far away he is.
Once you know your target’s distance, you can use the exact same measuring scale to correct for the drop of your bullet at that distance. Now you might understand why they call it weaponized math.
Accuracy Measurement
MOA is the most common method of measuring or stating the accuracy potential of a rifle. If your rifle shoots five shots at one hundred yards that measure one-inch center to center, then you can call that group a 1 MOA pattern. If your group measures 1.5 inches, you could call it a 1.5 MOA pattern.
As I mentioned before, an MOA is an angular measurement that increases with distance. One MOA at one hundred yards is about an inch, but it measures over ten inches at one thousand yards.
To be precise, one MOA is not one inch. One MOA is actually 1.047 inches at one hundred yards. And 10.47 inches at one thousand yards, but until you are shooting well enough to notice a ½ inch difference in your groups at one thousand yards, you can just work with the inch measurement.
How to Use Minute of Angle While Shooting
As soon as a bullet leaves the muzzle of a rifle, it begins to drop due to gravity and aerodynamic resistance. The further away the bullet travels, the more it drops, which requires corrective action to “hold over” the target high enough to hit it. But how much should I hold over, you might ask?
Long-range rifle scopes have corrective mechanisms to adjust for that drop. It is accomplished by either holding over the target using the same MOA scale you used to measure this guy, or you can use the turret of the scope to dial the corrective angular adjustment.
How Many Clicks are in an MOA?
Riflescopes that use MOA adjustments typically use turrets that are marked in either ¼ MOA per click or ⅛ MOA per click. One is no better than the other; you just need to know what you have. If you need to correct three MOA for a distant shot, it would be twelve clicks for a ¼ MOA scope turret vs. twenty-four clicks for a ⅛ MOA turret.
The same goes for reticles. Some scope reticles have half MOA markings or whole MOA markings. You need to familiarize yourself with whatever it is to ensure you make the right corrections.
Example: The above image shows a .569 MOA five-shot group. That measurement comes from the center of the two furthest apart bullet holes.
If your point of aim was the center of this target, and you wanted to center it up, you could measure the distance (approximately one inch left) and correct it by adjusting your scope one MOA or four ¼ clicks to the left.
Minute of Angle Formulas
There are several MOA formulas that you can use to estimate the distance of a target, as well as measure the size of the target. I’ve tried several of them over the years, and the one I find easiest to use is a set of binoculars called the Kilo 10K, which comes from Sig Sauer.
But seriously, if you want to learn the different equations, I recommend you study it online because I could go on for three more pages just about that subject. Here are a few resources I’ve found helpful, including a video:
- Sniper’s Hide – Stop the Debate, Mils vs MOA vs IPHY
- Millett Sights – Mathematics for Precision Shooters
MOA vs. Mil
I mentioned Milliradians or MRAD earlier. MOA and MRAD are the two most prominent units of measure for shooting. The difference between the two is like the differences between feet and meters. They are two different scales to measure the same thing.
Personally, I prefer MRAD because it is a little more coarse, and it works on a base-ten scale instead of quarters, halves, and such. So instead of correcting six and three-quarters MOA, you could use one point nine MRAD. Either one works fine. Pick the one that works for you and run with it.
How to Calculate 1 MOA Size at Your Distance
As I mentioned earlier, one MOA at one hundred yards is 1.047 inches. So to figure out one MOA at any given distance, you can simply multiply that number by the distance.
For Example: If the distance is 793 yards, you take 7.93 X 1.047= 8.3 inches.
How to Calculate the Bullet Drop
Every bullet drops at a given rate based on its velocity and the atmosphere it has to fly through. Ballistic calculators have made this part of weaponized math very easy. Without them, you need to either do a whole lot of math beyond my proficiency level or go out and shoot to figure out how much elevation correction it takes to hit at each given distance.
The latter can be very expensive with today’s ammo prices, so you’d be much better off spending 10-20 dollars to download a ballistic app. My personal favorite is Desert Tech’s Trasol.
Tips for Using MOA
Besides knowing the basic numbers like the 1.047 and such, it would be a good idea to know how to convert your MOA to MRAD in the likely event you are shooting with other shooters using the MRAD scale. You can go back and forth by multiplying or dividing your number by 3.438.
Example: 21.5 MOA divided by the 3.438 gives you 6.2 MRAD. You can quickly use these equations to go back and forth if needed. But if you’re terrible at math like me, it might be easier to make new friends with the same MOA type of scope you have.
FAQs
What does 4 MOA mean on a scope?
4 MOA is just 1 MOA four times, which, if you have a fairly standard ¼ MOA click scope, means you have to dial sixteen clicks to equate the four MOA.
How many inches is an MOA?
One MOA is 1.047 inches per hundred yards. So one MOA at 200 hundred yards would be 2.094 inches, and so on. At one mile, one MOA is 18.42 inches.
What’s better, 3 MOA or 6 MOA?
If you’re talking about accuracy, then three is obviously better than six. If you’re shooting six MOA, maybe go home and rethink your hobbies.
MOA is also often used as a size of a red dot. Some red dots have one MOA dot. Some have two MOA or three. This comes down to personal preference; a larger dot is easier to see but also covers up more of the target.
It seems easier to be more precise with a smaller (1MOA) red dot.
What Is Considered a Good MOA?
As far as accuracy is concerned, half MOA is considered good. Quarter MOA is exceptionally good, but for the most part, an excellent modern bolt-action rifle will typically shoot one MOA or better.
Conclusion
Hopefully, I’ve helped shed some light on this subject. At least enough to have a basic knowledge of the subject and something you can start learning.
MOA is an angular measurement suited for measuring ballistic corrections and deviations. It’s ideal for measuring these things because bullets travel and disperse in the same pattern. That is, they spread apart more and more as they travel away from their origin.
MOA has been the rule of ballistic measurement for much longer than I’ve been around. There is a great wealth of knowledge about the subject all over the internet. You’ve read what I’ve shared here. If you want more explanation on the subject, feel free to follow me or ask questions to start a conversation.
