Rifle Scope MOA Adjustment Calculator

MOA stands for Minute of Angle, one sixtieth of a degree. At 100 yards, 1 MOA equals 1.047 inches. At 200 yards it equals 2.094 inches; at 500 yards, 5.235 inches. Many shooters round to “1 inch per 100 yards” for quick mental math, which is close enough for most hunting ranges. The 4.7% you are throwing away by rounding is a twentieth of an inch at 100 yards and about a quarter of an inch at 500.

To find the MOA correction for a given impact error:

MOA = (error in inches / range in yards) × 95.49

Simplified: MOA ≈ error_inches × (100 / range_yards)

MIL (milliradian) is the other common unit. 1 MIL = 3.438 MOA = 3.6 inches at 100 yards. Tactical scopes often use MIL/MIL (MIL reticle, MIL turrets). Most American hunting scopes use MOA/MOA.

Common turret click sizes: 1/4 MOA per click: standard for most hunting and target scopes 1/8 MOA per click: finer, common on benchrest and precision long-range scopes 1/2 MOA per click: older military and budget scopes 0.1 MIL per click: standard for MIL-based tactical scopes

Click count = total correction / click size

Which way to turn it

Scope turrets are labelled by where the impact goes, not where the reticle goes, and that is the one thing worth being certain of. If your group is low, you dial UP. If it is left, you dial RIGHT. The arrow and the letter stamped on the turret are the authority: every maker prints them, and the rotation direction is not universal enough to memorise from a web page.

Do not try to reason it out from which way the reticle appears to move. That is the classic way to end up two corrections further from the bull than you started, having “fixed” it twice in the wrong direction.

Clicks do not divide evenly, and the leftover matters at distance

A 3 inch error at 100 yards is 2.87 MOA. On quarter-MOA turrets that is 11.46 clicks, and you cannot dial half a click, so 11 clicks lands you 2.75 MOA and leaves about a tenth of an inch on the table. At 100 yards nobody cares. The same fractional leftover at 600 yards is six times larger, which is why the calculator below prints the residual as well as the click count.

After applying your corrections, fire a 3-shot confirmation group before hunting or competition. The confirmation group tells you whether the adjustment landed where the math predicted, and it is the only part of this process that is not arithmetic.