MOA stands for minute of angle, which is one sixtieth of a degree. At 100 metres, 1 MOA covers 29.1 mm; at 100 yards it covers 1.047 inches, which is why shooters round it to "an inch at a hundred".
On optics, MOA is used for two things: the size of a red dot and the value of each turret click. Once you know that 1 MOA is about 29 mm at 100 m and scales with distance, you can work out both in your head.
Key takeaways
- 1 MOA = 1/60 of a degree = 29.1 mm at 100 m = 1.047 in at 100 yd.
- It scales with distance: 7.3 mm at 25 m, 14.5 mm at 50 m and 58.2 mm at 200 m.
- A red dot's MOA rating is its size: a 2 MOA dot covers 58 mm at 100 m.
- A 1/4 MOA scope click moves impact 7.3 mm at 100 m, so 14 clicks move it about 10 cm.
- MRAD is the alternative angular unit: 1 MRAD = 100 mm at 100 m.
What MOA actually measures
A full circle has 360 degrees, and each degree has 60 minutes, so 1 MOA is 1/21,600 of a circle. Because it is an angle rather than a length, the distance it covers on the target grows with range:
| Distance | 1 MOA covers |
|---|---|
| 25 m (27 yd) | 7.3 mm (0.29 in) |
| 50 m (55 yd) | 14.5 mm (0.57 in) |
| 100 m (109 yd) | 29.1 mm (1.15 in) |
| 200 m (219 yd) | 58.2 mm (2.29 in) |
| 100 yd (91 m) | 26.6 mm (1.047 in) |
Manufacturers print imperial figures because most optics are designed in the United States. British ranges are laid out in metres, so this page gives both. For every dot size and click value at every range, see the MOA at distance chart.
MOA and red dot size
A red dot's MOA rating tells you how much target the dot covers. A 2 MOA dot covers 58 mm at 100 m (2.1 in at 100 yd). A 3.25 MOA dot, the size used on the Trijicon RMR Type 2 3.25 MOA, covers 95 mm at 100 m. A 6 MOA dot covers 175 mm.
A bigger dot is quicker to find when you are moving fast up close. A smaller dot hides less of a small or distant target. Holographic sights such as the EOTech EXPS2-0 combine the two, with a 68 MOA ring around a 1 MOA dot. The red dot size chart goes into which size suits which job.
- 1 to 2 MOA: precise, better for rifles and distance, harder to find at speed.
- 3 to 4 MOA: a balance of speed and precision, common on pistol and general-purpose dots.
- 6 MOA and larger: the quickest to pick up at close range, and the least precise past 50 m.
MOA and turret clicks
Click values are also given in MOA. The common values are:
- 1/4 MOA: the usual value on hunting and target scopes. Each click moves impact 7.3 mm at 100 m (0.26 in at 100 yd). Burris gives this value for its Fullfield E1 3-9x40.
- 1/2 MOA: common on LPVOs and red dots. Each click moves 14.5 mm at 100 m. SIG gives this value for the TANGO-MSR 1-6x24.
- 1 MOA: found on some red dots. Each click moves 29.1 mm at 100 m.
Worked example: your group is 50 mm low at 100 m and your scope has 1/4 MOA clicks. 50 ÷ 7.3 = 6.9, so dial 7 clicks up. At 25 m each click moves only a quarter as far (1.8 mm), so the same shift in impact takes four times as many clicks. The full process is in how to zero a rifle scope.
What "sub-MOA" means
When a rifle or load is described as "sub-MOA", it means it groups inside 1 MOA: under 29 mm at 100 m, or about an inch at 100 yd. It is a measure of the rifle and ammunition, not the optic. A scope cannot make a rifle more accurate, but loose rings or poor tracking can make it less accurate.
MOA vs MRAD
MRAD (milliradian, or "mil") is the other angular unit. 1 MRAD covers exactly 100 mm at 100 m, or 3.6 in at 100 yd, and a 0.1 MRAD click moves 10 mm at 100 m. That base-10 arithmetic is why many metric shooters prefer it. One MRAD equals 3.44 MOA, so neither is finer or more accurate in itself. What matters is that your reticle and turrets use the same unit. The full comparison is in MRAD vs MOA explained.
UK note
UK ranges and zero distances are usually metric, but "1 inch at 100 yards" is the rule of thumb everyone quotes. At a 100 m range, 1 MOA is 29 mm, not 25 mm, so if you measure in millimetres and assume 25 mm per MOA, you will dial about 15% too many clicks. Learn the metric figure and you will not need to convert.
Frequently asked questions
What does MOA mean on a red dot?
It is the size of the dot as an angle. A 2 MOA dot covers about 58 mm at 100 m, or 2.1 in at 100 yd. Smaller dots are more precise; larger dots are faster to find.
How much is 1 MOA at 100 metres?
29.1 mm. It scales with distance, so it is 7.3 mm at 25 m, 14.5 mm at 50 m and 58.2 mm at 200 m.
Is a 2 MOA or 6 MOA dot better?
A 2 MOA dot is better for precision at distance, particularly on a rifle. A 6 MOA dot is quicker at close range, which is why it is popular for fast pistol and shotgun shooting.
How many clicks is 1 MOA?
Four clicks on a 1/4 MOA scope, two on a 1/2 MOA optic and one on a 1 MOA optic. The click value is printed on the turret or in the manual.
Shop this guide
- Red Dot Sights — dot sizes from 1 to 8 MOA, stated in every listing.
- Rifle Scopes — MOA and MRAD scopes for stalking, target and practical shooting.
- Pistol Dot Sights — compact dots in 2 to 6 MOA sizes.
