If you use a scope on a gun, or sometimes a bow, you will come across the acronym MOA. So what is MOA on a scope? Does MOA matter to shooting accuracy?
MOA stands for Minute of Angle. MOA is a scope adjusts the reticles. In short, MOA is a unit of measurement. More specifically, 1 MOA is 1/60th of a degree. 1 MOA is an angular measurement. A degree is a measurement of an angle. A right angle is 90 degrees at the point where the two lines meet. A circle has 360 degrees. A perfect square has four right angles, one at each of the corners.
No matter how big or small the circle is, it will always have 360 degrees. No matter how big or small a right angle is, it always has that 90-degree corner. Angular measurement does not change. MOA size in minute of angle does not change either. 1 MOA is always 1 MOA no matter the distance between the outer points on the arc. However, the distance that MOA covers changes over a certain distance. More about arcs below.
The National Shooting Sports Foundation has a video explaining how MOA is an angular measurement to help you understand it more.
I am Ben Baker, a lifelong hunter and almost life-long outdoor journalist. I have sighted in many scopes using the MOA adjustment. In this article, I will share more information about minute of angle and how it is used in shooting scopes.
Know About Minute Of Angle
You need to know about Minute Of Angle because this is the most common scope adjustment measurement. The other unit of measure is Milliradians, abbreviated MRAD or MIL. Both are angular measurement. MIL is used by the military and people who want extreme precision in their scopes. We will discuss the difference in the two below.
If 1 MOA is a measurement of part of a degree and degrees are found in circles, then why is it used in scopes? Because bullets do not travel in a straight path. Bullets drop. The path of a bullet and the bullet drop can be expressed as MOA. Figuring a bullet's path is not linear measurement.
Imagine a gun barrel is a laser. It holds a perfectly straight line across any given distance. A bullet does not because of bullet drop.
Now put that laser dot on a target 100 yards away. Load the gun and fire it. The bullet drop means the bullet impact is below that dot. The bullet drop depends on the given distance, the ballistics of the gun and the cartridge.
Here is the important part. People want to know how many inches per MOA. It varies. At 100 yards, 1 MOA at that distance 1.047 inches. That is usually rounded off to an inch. At 500 yards, 1 MOA at that distance is 5 inches. At 1,000 yards, 1 MOA is 10 inches. At 50 yards, 1 MOA is a half inch. When you understand MOA, you can calculate the minute of angle at any distance. You also see why MOA size matters and now the inches per MOA change over a distance.
Also, Discover the secrets to hitting the X ring at 1,000 yards consistently in our coverage of the 50 BMG World Championships.
An Arc
If you sight your gun in at exactly 100 yards, then at 50 yards, the bullet hits high. At 200 yards, the bullet hits low. Why? Bullet drop. The bullet travels in an arc. Arcs are measured in degrees. Linear measurement only works here in computing the distance to the target.
Relative to the plane of the barrel, that laser I mention above, the bullet drops begin as soon as the projectile leaves the barrel. This is the arc.
An arc can be measured with degrees as mentioned above. Those degrees can be further broken down into minutes.
Gun Data has a ballistics chart to show you bullet drop for a given caliber. Using their data for an extreme example, take a .25 ACP pistol round sighted in at 100 yards. You can see how the distance affects the Minute of Angle.
If the barrel is a laser, then the laser beam is 8.1 inches above the 100-yard if you shoot at 50 yards. At 50 yards, 1 MOA is a half inch. The adjustment needed is about 16 MOA because 2 Minutes of Angle equals an inch at 50 yards.
That means over the next 50 yards in distance, the bullet drop is 8.1 inches. MOA size is 1 inch at 100 yards. So, the adjustment needed is also 8 MOA.
At 150 yards distance, the bullet drop is 28 inches below the laser beam as centered at 100 yards. At 150 yards distance, 1 MOA is 1.5 inches.
Because I am terrible at math, I have to break this down.
At 100 yards, 28 inches is 112 MOA. Fifty yards is half 100 yards. Half 112 MOA is 56 MOA. So, 112 MOA plus another 56 MOA is 168 MOA. That is a HUGE adjustment in MOA or inches.
That kind of shooting requires special custom-made scope mounts to account for the needed MOA and bullet drop.
Two Arcs
When you are working with MOA and a shooting scope, you have two arcs to deal with. You have the elevation arc, up and down, and the windage arc, left and right. Bullet drop does not matter to windage. It does matter in distance.
Once you set the windage, you rarely adjust unless you are shooting in windy conditions. Most precision and many tournament shoots have scopes that allow shot-to-shot windage adjustments to compensate for wind.
You will adjust your scope's windage when sighting it in.
Elevation, once you sight your gun in, can be changed by where you set the sights on the target. If you are close, aim a little low. If you are past the distance at which your scope is sighted in, aim a little high. This is called holdover. Experience in shooting at different distances will tell you the needed holdover to account for the bullet drop.
MOA Matters
Minute of angle matters because this is the most common turret adjustments in the elevation, or distance, and windage MOA turrets. This how you adjust for bullet drops.
The most common increment is 1/4 or .25 of 1 MOA. This is also called the click value. It is called click value because the scope turret usually makes a slight "click" noise with each adjustment. With the value at .25 MOA, you need to get four clicks to move the optic's reticle an inch at 100 yards.
A few precision MOA scopes have a 1/8th MOA click value. Some may even have a 1/10th MOA, but these are the very top-of-the-line scopes and usually found on rifles costing thousands of dollars.
Some red dot and reflex sights may have click values of 1/2 or even 1 MOA on handgun scopes. The dot inside the red dot scope is also measured in MOA.
MOA depending on the optic. A 6 MOA dot will cover 6 inches of target at 100 yards. A 3 MOA red dot covers 3 inches of the target at 100 yards.
Check out this article on the Best Handgun Scopes by Gary Anderson.
Moa Changes
The measurement of 1 MOA never changes. It is always 1/60th of a degree. At the same time, the space 1 MOA covers gets larger as the distance to the target increases. That is hard for some people to understand.
At 100 yards distance, if you are off by one minute of angle, you are off an inch. At 1,000 yards, if you are off one MOA, you are off 10 inches.
Sighting In
If you use a typical minute of angle target for sighting in, the horizontal and vertical lines are one MOA apart respectively at 100 yards. Other MOA targets may be set for 25 or 50 yards or even greater distances depending on the shooting range.
This makes sighting in easy. Once you get on the paper, then you know how much you need to adjust to get centered.
Example:
Your scope has 1/4 minute of angle adjustments or click values.
Your shot is 5 squares left and 3 squares low. How many MOA adjustments are needed? You need 5 MOA adjustment to the right and 3 MOA adjustment on the elevation turret. That is 5 inches to the right or 20 MOA and 3 inches up or 12 MOA.
Four clicks up is 1 inch or 1 MOA in the elevation turret.
You need to go 3 inches up or 3 MOA adjustments up up so 3 x 4 = 12. You need 12 clicks of elevation.
Four clicks right is 1 inch or 1 MOA adjustment. Since you are 5 inches off or 5 MOA off, you can figure 4 x 5 = 20. You need 20 clicks to the right. You can count the shift 1 MOA at the time by listening for the click or feeling it.
Does your scope have that much adjustment? Most scopes have 60-100 MOA of adjustment in elevation and windage.
Adjustments
The MOA turrets on your scope will show you which direction to turn for the adjustments.
Turn it slowly. This is not a race. Feel the click as you turn the dial.
Some dials have a groove. You can use a key, a penny or dime in the slot to make the turn. Others have a raised piece you can grip with your fingers or pliers if needed.
When you have made the needed MOA adjustments, shoot again. You may need to shoot a few more times to get it dialed in exactly right.
Smaller MOA adjustments give you more precision when trying to hit the target.
Tips For Using MOA
Once you get your scope sighted in, MOA becomes less important unless you are using a scope with in-field adjustable MOA turrets, an MOA reticle or a scope with both.
Adjustable Turrets
If you have adjustable turrets, you sight in your rifle the usual way. Then, lift the cap slightly so the reticle adjustment will not turn. Turn the cap until it is set to zero on the line on the turret.
When you are shooting, you can turn the turret cap to adjust windage and elevation. When you are done, gently twist the cap until the zero is lined up again.
You have to know MOA adjustments in this case. Ballistics charts can help you decide how many MOA adjustments you need for the shooting you are doing. Experience will teach you how to calculate MOA adjustments in the field.
Adjustable turrets are used by long range, precision and tournament shooters.
MOA Reticles
MOA reticles generally come in two styles. This article will help explain reticles.
1) Standard. This MOA reticle has hash marks on the elevation line and the windage line. Some have the hash marks only on the windage and the lower half of the elevation line. The hash marks are 1 MOA apart.
This scope takes some educated guesswork to make a shot that is not lined up on one of the reticle hairs.
2) Christmas Tree. A Christmas Tree reticle has marks on the lower half of the scope that branch out to the sides. It looks like a tree, hence the name Christmas Tree. These lines are 1 MOA apart. This reticle is a favorite in long range shooting. It will help calculate the windage and elevation.
You can look through this kind of scope and line up your shot in the bottom half of the scope on the right or the left with the reticle hairs.
Some scopes have Christmas Tree reticles and adjustable MOA turrets. If you are serious about long range shooting, invest in this kind of scope.
These scopes are often used for long-range shooting. Take a look at our top picks for these scopes.
MOA Vs MIL
Minute of Angle or Milliradian, which is better? The short answer is neither is better than the other for most shooters. Both are measurements of a circle.
Here is the quick difference.
Minute of Angle uses inches and yards.
Milliradian uses centimeters and meters.
The US military started using MILs in WWI for artillery. The idea took off from there, which is why the military uses it now. MILs are a standard unit for scopes, especially for precision shooters.
Hunting Mark's other scope reviews often have a discussion of MOA v MIL.
Which is easier to use? For most Americans, that is the MOA system because they are more familiar with Imperial measurements (inch, foot, yard) than the metric system. If you have a solid grasp of the metric system, an MIL scope might be the best choice.
Which is more accurate? The MOA system has a slight edge here. The most common 1/4 of 1 MOA covers less space than 1/10 of an MIL. The average shoot will not be able to tell the difference between 1/10 of a meter in MIL compared to 1/4 of an inch in 1 MOA.
If you need to convert between the two, Brandon Maddox at Silencer Central offers this formula to calculate MOA.
- MOA to MIL: MOA / 3.438 = MIL
- MIL to MOA: MIL * 3.438 = MOA
- His article is an excellent discussion on MOA v. MIL.
You can check out Hunting Mark article on "Best Red Dot For 45 Degree Mount".
Final Thoughts
To me, MOA is easier to manage than MIL. I can shoot with either on a rifle.
If you have two scopes of equal quality, one in MOA and one in MIL, then the difference in accuracy is going to be in the gun, the shooter and the ammo. In my case, most of my guns and the ammo I shoot are better than I am. I am particular about the scopes I buy.
