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MIL vs MOA: Conversions, Click Values and Where the Precision Goes

Exact MIL and MOA conversions, why 1 MOA is not 1 inch at 100 yards, how to range with the mil-relation formula, and what each shortcut costs at 600 and 1,000 yards with a 6.5 Creedmoor.

6 min readSolved with the Ballista engineUpdated October 2026

A 1/4 MOA click is not a quarter inch at 100 yards. It’s 0.262 in, and the difference is enough to put a 1,000 yard shot 14 inches low if your calculator and your turret disagree about which “MOA” they mean. MIL and MOA are both exact angles, and either one works. Precision gets lost in the conversions and shortcuts between them, and in turret labels that don’t say what they mean.

Two angles, exactly

A milliradian (MIL) is a thousandth of a radian. At 100 yd it covers 3.6 in, because 100 yd is 3,600 in. At 100 m it covers 10 cm. There’s nothing to round: the unit was made for decimal arithmetic.

A minute of angle (MOA) is 1/60 of a degree. At 100 yd it covers 1.0472 in. That’s close to an inch, which is why people say “one inch at 100”, but it isn’t one.

The exact link between them: 1 MIL = 3.4377 MOA, and 1 MOA = 0.2909 MIL.

A third unit hides inside some MOA scopes. IPHY, inches per hundred yards (also called “shooter’s MOA”), is exactly 1 in at 100 yd, or 0.9549 true MOA. It’s 4.5% smaller than a true MOA.

Both common click values are fine resolution for field shooting. A 0.1 MIL click moves 0.36 in at 100 yd and a ¼ MOA click 0.262 in. The ¼ MOA click is finer, about 1.38 of them per 0.1 MIL, and neither will limit a rifle that shoots under 1 MOA.

Where the precision really goes

We ran each common mistake through the come-ups for both rifles. The table puts the size of the miss next to the unavoidable error from rounding to the nearest click.

The IPHY trap. The 6.5 needs 30.42 MOA at 1,000 yd. Dial 30.42 on a turret whose clicks are really a quarter inch at 100 yd and you’ve applied only 29.05 true MOA. The shot lands 14.4 in low. The error is proportional to the dial, so it hides at short range and shows up as “my BC must be off” at long range. The cure is to set the calculator to the unit your turret really moves, which you find out by measuring it, or from the maker’s spec sheet. The scope tracking article covers the test.

Rounded conversions. A shooter with a MIL scope who thinks in MOA, or the reverse, may convert with 3.5 or 3.4 instead of 3.438. Neither is much of a rounding, but it’s applied to the whole come-up. At 1,000 yd 3.5 puts the 6.5 5.8 in high. Don’t convert at all: set the calculator to the scope’s own unit, and keep the reticle and turret in the same unit.

Rounding to clicks. This one you can’t avoid. At 1,000 yd the nearest 0.1 MIL click can be up to 1.8 in off and the nearest ¼ MOA click 1.3 in. It’s the floor of what your system can do, and a careless conversion easily adds more than that.

The mil-relation formula, and its traps

MIL reticles make ranging arithmetic simple. With a target of known size, read its size in MILs in the reticle and:

range (yd) = target size (in) × 27.78 ÷ MILs read
range (m) = target size (mm) ÷ MILs read

The 27.78 is 1,000 ÷ 36. The MOA version is range (yd) = size (in) × 95.5 ÷ MOA read, with 95.5 = 100 ÷ 1.0472. In IPHY it’s size × 100 ÷ IPHY read.

The arithmetic is exact enough. Reading the target is not, and the error grows fast with distance because the target gets smaller in the reticle while your reading resolution stays the same.

An 18 in plate at 600 yd reads 0.83 MIL. Misread it by just 0.1 and you get 536 yd instead of 600, and the dialed shot misses by more than the plate’s half-width. At 1,000 yd a 0.1 MIL misread is the difference between a hit and a miss by feet. That’s why a laser rangefinder beats reticle ranging past a few hundred yards. The reticle ranging article goes deeper into the error.

The meter column is another common slip: using size in inches × 25.4 ÷ MILs gives the range in meters, not yards. Read it as yards and you dial for a range 8.6% short.

Pick one and stay in it

The angle unit matters less than using one unit consistently. A few practical points decide it for most people:

• MIL is easier to talk about. Corrections are short decimals (“up 4.3, left 0.4”), and a spotter with the same reticle can call a miss in the same units without conversion.
• MOA gives finer clicks at ¼ MOA, and suits people who think in inches at 100 yd, as long as everyone remembers 1 MOA is 1.047 in.
• Reticle and turret must match. A MIL reticle with MOA turrets forces a conversion on every shot.

In Ballista you choose the scope’s Turret clicks in the rifle profile: 0.1 MIL, 0.05 MIL, 1/4 MOA, 1/8 MOA, 1/2 MOA, or 1/4 in @ 100 yd for IPHY turrets. Corrections then show in that unit, rounded to your clicks, so there’s nothing to convert at the rifle.

A short checklist

1. Confirm what your turret really moves. Run a tall-target test, or read the maker’s specs for “MOA” versus “IPHY”.
2. Set the calculator to that exact unit and click value. Never convert a come-up by hand.
3. Use the same unit for reticle and turret.
4. If you range with the reticle, measure as precisely as you can and treat ranges past about 600 yd as estimates.