What MOA Means on a Red Dot Sight: Dot Size and Click Value

Two specifications on a red dot sight are given in MOA, and they have nothing to do with each other. One is the size of the dot — how much of the target your aiming point hides. The other is the click value on the turrets — how far one click shifts where the shot lands. Keeping them apart is most of the battle, and the arithmetic for both fits on a target card.

One minute of angle, defined once

A minute of angle is one sixtieth of a degree. It is an angle, not a length — the idea everything else depends on. An angle opens out as it travels, so the patch of target one MOA covers grows with distance while the number never changes. Your 2 MOA dot is 2 MOA at 10 yards (9 m) and at 200 (183 m); what changes is how much of the world it sits on.

Run the trigonometry and one MOA subtends 1.047 inches at 100 yards (91 m), or 2.9 cm at 100 metres (109 yd). Everyone rounds that to "an inch at a hundred yards", and the rounding is honest: it overstates the correction by under 5%, less than your group size. Think in round numbers; remember the 1.047 exists.

Job one: how much target the dot covers

Multiply the dot's MOA figure by the distance in hundreds of yards for its coverage in inches. Everything below is that sum.

Those are real reticles: the Trijicon SRO comes in 1.0 and 2.5 MOA, the RMR Type 2 and RCR use 3.25 MOA, the Holosun HS407K-X2 6 MOA.

Reading the table against what you actually shoot at

Coverage means something only next to a target size, so put your own numbers beside it. If the reduction target or kill zone in front of you is 40 mm across at 25 yards (23 m), a 6 MOA dot covers all 40 mm — it vanishes behind the aiming point and you are guessing at centre. A 2 MOA dot covers 13 mm of it, leaving most of the ring to judge by. Neither is more accurate; one lets you see.

Scale that to your discipline. Airsoft in woodland happens well inside those distances, where even a 6 MOA dot covers under an inch on a torso-sized target. Hunter field target is shot further out against small, precisely defined reductions, and there the gap between 2 MOA and 6 MOA stops being academic. Deliberate shooting at a small vital area is the same argument: at 100 yards (91 m) a 6 MOA dot sits on 6.3 in (160 mm).

Both carry limits worth stating properly. Hunter field target is shot with air rifles, and the Guide on firearms licensing law sets the exempt thresholds at 12 ft lb for an air rifle and 6 ft lb for an air pistol (s.2.46). Airsoft sits under a separate definition: Firearms Act 1968 s.57A defines an airsoft gun as a barrelled weapon designed to discharge only a small plastic missile, spherical and no more than 8 mm across, not capable of exceeding 1.3 joules where it fires two or more missiles successively without repeated trigger pressure, or 2.5 joules otherwise. Scotland runs its own air weapon certificate scheme under s.2 of the Air Weapons and Licensing (Scotland) Act 2015; Northern Ireland has its own firearms legislation (s.4.5). Confirm what applies to you with your police firearms licensing department, or Police Scotland.

Why a bigger dot is not a worse dot

A large dot is found faster; the eye picks up a bright 6 MOA blob almost involuntarily, while a 1 MOA pinprick has to be located, and in poor light that search costs time. A small dot is more precise, because you can see the target underneath. That is the whole trade, and it resolves in favour of whatever you shoot most.

A circle-dot reticle is the usual attempt at both, and it works better than a compromise dot size does. The Holosun HS507C-X2 gives a 2 MOA dot, a 32 MOA circle, or both; the HS510C pairs the same dot with a 65 MOA circle; the SIG ROMEO5XDR Gen II puts a selectable 65 MOA circle around a 2 MOA dot; an EOTech XPS2-0 uses a 68 MOA ring with a 1 MOA dot. The ring is what the eye catches at speed; the dot is what you aim with.

Job two: how far one click moves the shot

The same unit now measures something else. A click value of 1 MOA means one detent moves the point of impact by one MOA — about an inch at 100 yards (91 m), proportionally less closer in.

At 100 yards (91 m) your group sits 4 inches (10 cm) below the aiming point — 4 MOA of error. With 1 MOA clicks that is 4 clicks up; with 0.5 MOA clicks, 8 clicks up. Nothing changed but the size of the step you move in.

The bit that catches people out: shorter distances

Now zero at 25 yards (23 m) instead, still 4 inches (10 cm) low. One MOA is only about a quarter of an inch there, so 4 inches is roughly 16 MOA of error — four times the correction of the identical miss at 100 yards (91 m). That is 16 clicks on a 1 MOA optic and 32 on a 0.5 MOA one. Shooters who learn "four inches low, four clicks" at 100 yards (91 m) then move to a short range dial a quarter of what they need and decide the turret is broken.

Metric changes only the constant: one MOA is 2.9 cm at 100 m (109 yd), 1.45 cm at 50 m (55 yd), 0.73 cm at 25 m (27 yd). A group 5 cm low at 50 m (55 yd) is about 3.4 MOA out: three clicks on a 1 MOA optic, seven on a 0.5 MOA one. The procedure around the arithmetic is in how to zero a red dot sight.

When the click value will not divide evenly

The 1.5 MOA click misbehaves. At 100 yards (91 m) a 4 MOA correction is 2.67 clicks, and there is no such thing: take three and land 0.5 MOA high, or two and stay 1 MOA low. The ROMEO-X Pro, ROMEO-X Compact and ROMEO-M17 are all specified at 1.5 MOA per click. Zeroed at 25 yards (23 m) that residual is about 0.1 in — a non-issue in practice, worth knowing only so it does not read as a fault.

Click values across the optics we stock

Click value is rarely on the box, and varies more within a brand than between brands. Every figure below is from the technical specification on the product page.

A dash means the specification we hold states no travel figure; we would rather leave it blank than estimate. Note that the Holosun rifle optics here step in 0.5 MOA while the pistol optics step in 1 MOA, and SIG's range runs across all three values. Brand is not a reliable guide; the specification is.

Fine clicks are not extra adjustment

The travel column is routinely misread. Travel is an angular range fixed by the mechanism; the click value only decides how many steps it divides into. The HS510C has ±50 MOA in 0.5 MOA steps — 200 clicks end to end. The HE508T-X2 has the same ±50 MOA in 1 MOA steps — 100 clicks for the same correction range. Halving the click value doubles the turning, not the reach.

Travel matters when the optic has to correct for more than a small manufacturing offset: a mount off-axis, a rail not quite true, a cut a shade out. The compact HS407K-X2's ±30 MOA is the tightest range here — normal for a small body, and worth knowing before you ask turrets to rescue a mounting problem instead of fixing the mount.

What the two numbers decide between them

Dot size is decided once, at purchase, and lived with: it sets the finest thing you can aim at, and only a switchable reticle changes it. Click value is decided for you and costs nothing but turret time — a 0.5 MOA optic is not more accurate, it reaches the same zero in twice as many clicks. Between two sights, finer clicks are the smaller difference.

One practical note: we sell optics, magnifiers and mounts, nothing else. Targets, a bore sighter and a rest come from a general shooting supplier.

With dot size settled the next constraints are mechanical — whether the sight fits, in red dot sight footprints explained, and whether the emitter is exposed or sealed, in open reflex vs enclosed red dot sights. Dot size is listed on every entry in the red dot sights range; multi-reticle optics gathers the sights that let you change it.