Air Rifle Accuracy
Mil-Dot Ranging: Judging Distance with Your Reticle
A pellet's flight is a steep arc, so the single most useful thing you can know before a shot is the range — and the marks already in your scope can give you a rough one. Mil-dot ranging is an old military rangefinding trick: if you know roughly how big the thing you're looking at is, the amount of reticle it covers tells you how far away it is. Here's the simple version for airgunners, and an honest look at where it actually helps.
The idea in one sentence
The marks on a ranging reticle measure angle — how big something looks — not size. A rabbit that looks "two marks tall" up close looks "one mark tall" twice as far away. So if you know the rabbit's real height, the number of marks it fills tells you the distance. That's the whole trick: known size + measured angle = range.
Two ways of marking the same thing. MRAD (mils) and MOA both measure angle — they're just different rulers. Mils divide neatly into metric distances, which is why range estimation usually uses them.
The formula
For mils and metric, the sum is about as easy as it gets:
If you prefer MOA and yards, the same logic gives distance (yd) = height in inches × 95.5 ÷ MOA. The numbers are less tidy, which is the practical reason most people who range off the reticle do it in mils.
A worked example
A rabbit sitting up alert is roughly 25 cm from the ground to the tip of its ears. Settle the reticle on it and you read about 6 mils top to bottom. Drop it into the formula: (25 × 10) ÷ 6 = about 42 metres. That's all there is to it — and now you know which holdover to use instead of guessing.
Rough sizes of UK airgun quarry
You can only range off a dimension you can actually see, so match it to how the animal naturally sits in front of you. Ground game is horizontal — range a rabbit, rat or squirrel by its length, side on. Birds perch upright — range them by their standing height, not their beak-to-tail length, because on a live bird most of that length is tail and extended neck you can't reliably measure.
| Quarry | Dimension to range | Approx. size |
|---|---|---|
| Rabbit (alert) | Sitting upright — ground to ear tip | ~25 cm |
| Rabbit (feeding) | Length, side on | ~38–42 cm |
| Grey squirrel | Length, head & body, side on | ~25 cm |
| Brown rat | Length, head & body, side on | ~22–25 cm |
| Woodpigeon | Perched height | ~25 cm* |
| Feral pigeon | Perched height | ~20 cm* |
| Carrion crow | Perched height | ~28 cm* |
| Magpie | Perched height (excl. trailing tail) | ~22 cm* |
These are approximate adult figures for building intuition — real animals and posture vary, so verify against known distances on your own permission. *Bird heights are rough field estimates: references publish beak-to-tail length, not standing height, so calibrate them on birds at ranges you already know. A bird that turns head-on gives you nothing reliable to measure — wait for it to settle side-on or upright.
A quick ranging reference
How many mils common quarry covers at typical airgun ranges. Read your reticle, find the closest match, and you have a range without lifting a finger off the rifle. The columns are sized to the two most common references: ~25 cm (sitting rabbit, squirrel, perched woodpigeon) and ~40 cm (a rabbit feeding side-on).
| Range | ~25 cm quarry | ~40 cm quarry |
|---|---|---|
| 25 m | 10.0 mils | 16.0 mils |
| 30 m | 8.3 mils | 13.3 mils |
| 35 m | 7.1 mils | 11.4 mils |
| 40 m | 6.3 mils | 10.0 mils |
| 45 m | 5.6 mils | 8.9 mils |
| 50 m | 5.0 mils | 8.0 mils |
Where it actually helps — and its limits
Be honest with yourself about this technique. It was built for stalking rifles ranging large animals out to hundreds of yards, where small subtensions give fine resolution. At airgun ranges the targets are small and close, so they fill a lot of reticle and the readings are coarse — a couple of mils can be the difference between 30 and 45 yards. It's a useful sanity check and a brilliant way to train your eye, not a laser rangefinder.
Two practical traps to know about:
- Second focal plane scopes. Most airgun scopes are SFP, meaning the reticle stays the same size while the image zooms. The mil spacing is only correct at one magnification (usually max power, or a stated setting). Range at the wrong zoom and every number is wrong. First focal plane reticles hold true at any magnification.
- It's an estimate, not a measurement. Posture, your read of the marks and the animal's true size all introduce error. Where the shot has to be humane, treat the reticle figure as a starting point and back it up with experience of the ground.
Shoot legally and within humane range. A sub-12 ft·lb air rifle has a short effective range for a clean kill — far shorter than the pellet will travel. Only take shots you know are within that range and your own ability, and only at legal quarry, in season, with the landowner's permission and under the relevant general licences.
Air weapon law and quarry rules differ across the UK and change over time — for example Scotland requires an air weapon certificate. This guide is general information, not legal advice; check current guidance from official sources such as gov.uk and a body like BASC before you head out.
Ranging only pays off if you know your holdover. Estimating 35 yards is no use unless you know exactly where your pellet lands at 35 yards — and that comes from your own zero and trajectory, logged in your own conditions. Pellet records every group next to the distance and weather it was shot in, so your holdovers are built on your real data, not a generic chart.
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Frequently asked questions
How do you use a mil-dot reticle to estimate range?
Measure how many mils of the reticle the quarry covers, then use: distance in metres = (height in cm × 10) ÷ mils read. A rabbit about 25 cm tall covering 6 mils is roughly 42 metres away.
What's the difference between MOA and MRAD for ranging?
Both measure angle. MRAD (mils) divides neatly into metric distance — one mil is a thousandth of the range — so the maths is simpler. MOA works identically but the arithmetic is less tidy, which is why ranging is usually done in mils.
Does it work on a second focal plane scope?
Only at the magnification the reticle is calibrated for, usually maximum power or a stated setting. On an SFP scope the reticle stays fixed while the image zooms, so the spacings are only true at that one zoom. FFP reticles are correct at every magnification.
Why does range matter so much for an air rifle?
A pellet is light and slow, so its path is steeply curved. A few yards of range error becomes inches of impact error — the difference between a clean shot and a poor one. Knowing the range is what lets you apply the right holdover.