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Ever been reading about shooting or talking to other shooters and hear the expression MOA and not really understood what it meant or how it was applied to shooting? I've heard some really interesting theories and descriptions on MOA including:

• Millimeter of angle


• Minutes of angle (as in time)


• Mark of angle

While I could try to explain MOA in detail, the article below written by Stephen Fischer from ClearlyOptics.com does a far better job than I ever could.

MOA, or Minute of Angle, is really a popular dimension for describing various capabilities in rifle scopes and shooting. It is most usually utilized to describe the click value for windage and elevation turrets on rifle scopes. The click value is how much the reticle moves per one click on the turret. Values from 1/8 to 1 MOA are generally encountered.

As a basic rule of thumb, most shooters say that 1 MOA equals 1 inch at 100 yards. By extension, that would be a couple of inches at 200 yards, 3 inches at 300 yards, etc. The smaller the click value, the a lot more accurate the windage and elevation adjustments will be on your rifle scope. This accuracy can be important during competitive shooting and for long-range shots. On top of that, understanding the circle size in circle dot reticles helps make rifle scopes useful for rangefinding purposes.

In a fundamental explanation of MOA, we'll start with a circle. Naturally, a circle is a mathematical figure where all points are equidistant from a single point, known as the center. The distance from the center to the circle may be the radius and a segment of the entire circle is called an arc. The circle is divided into 360 degrees and every degree is divided into 60 minutes. Returning to our rifle scopes for a moment, one MOA is 1/60th of one degree.

For our example, we'll use a circle with a radius of 1. Let's say it's 1 yard. If you paid attention in that geometry class, you'll remember that a circle with a radius of 1 is called a Unit Circle. Utilizing a unit circle makes the math easy. The circumference of the circle is determined by the formula, 2(pi)r, wherever r is the radius and pi is the constant worth three.14. Pi is actually one of those infinite decimals that keeps going on and on but we'll stop it at decimal 2 points for our exercise.

So, our circumference is a couple of times three.14 times 1 or 6.28. Now we wish to figure out the length of an arc determined by one MOA. So, 6.28/360 degrees is 0.0174 and we'll divide that by an additional 60 minutes to get 0.000291. Of course, we don't need rifle scopes to shoot anything one yard away, but we can calculate the length of an arc at 100 yards. To do so, we'll merely multiply the 0.000291 times 100 to obtain 0.0291. Easy math right? Now, to convert that to inches we'll multiply it by 36 since there are 36 inches in a yard. So, 0.0291 * 36 = 1.0476

When peering via a rifle scope at a target 100 yards away, 0.0476 is really a fairly minor amount so we merely rely on our rule of thumb that 1 MOA equals 1 inch at 100 yards.

Tags: minute of angle for scope, MOA of a riflescope, Scope MOA, Understanding MOA in Shooting