MOA vs MIL

Last updated: 2026-05-05 · 9 min read

Angular measurement: the underlying concept

Both MOA and MIL are angular units. They describe an angle at the observer, not a linear distance downrange. Because the angle is fixed and the triangle grows with distance, the linear size of one MOA or one MIL at the target scales proportionally with range.

This is useful because a single correction dialed on the scope — say, 2.5 MIL of elevation — produces the correct impact shift regardless of the target distance, as long as you know the distance and use it in the calculation. The angular unit is range-independent; the resulting linear impact shift is not.

An analogy: hold your thumb at arm's length and note how wide it appears. At arm's length, one thumb-width subtends roughly 2°. Against a wall 10 feet away that angle covers about 4 inches; against a wall 100 feet away it covers about 42 inches. The angle stayed constant; the linear span changed with distance. MOA and MIL work the same way — fixed angles, variable linear spans that grow predictably with range.

Minute of Angle (MOA)

A circle is divided into 360 degrees. Each degree divides into 60 minutes of arc. One MOA is therefore 1/60th of one degree, or 0.01667°. At any given range, the linear span of 1 MOA is:

linear span = range × tan(1 MOA)
             = range × tan(0.01667°)
             = range × 0.0002909

At 100 yards: 100 × 0.0002909 = 0.02909 yards = 1.047 inches. This is the canonical "1.047 inches at 100 yards" figure. It is common practice — and a useful approximation — to round this to 1 inch per MOA at 100 yards. The error from this rounding is 4.7%, which becomes 0.5 inch at 1,000 yards: acceptable for most field work, worth noting for precision load development.

Most precision rifle scopes offer 1/4 MOA per click (0.25 MOA = 0.262" at 100 yards). Competition-oriented scopes sometimes use 1/8 MOA per click (0.131" at 100 yards) for finer resolution.

Milliradian (MIL / MRAD)

A radian is the angle subtended by an arc equal in length to the radius of the circle. One radian = 1,000 milliradians. At any range, the linear span of 1 MIL is:

linear span = range × tan(1 mrad)
             = range × 0.001        (exact for small angles)
             = range / 1000

At 100 meters: 100 m × 0.001 = 0.1 m = 10 cm. At 100 yards: 100 yd × 0.001 = 0.1 yd = 3.6 inches. The 1/1000 relationship is exact for practical purposes — MIL is inherently base-10 when working in metric. One MIL at 100 m is always 10 cm; one MIL at 500 m is always 50 cm.

Tactical and military scopes typically use 0.1 MIL per click (1 cm at 100 m, 0.36" at 100 yd). Some precision competition scopes offer 0.05 MIL per click for maximum resolution.

MOA vs MIL: side-by-side reference

Click values are for the most common precision scope increment: 1/4 MOA and 0.1 MIL. Scope specifications vary by manufacturer. Always verify against the product manual.

Both units scale linearly with range. A 0.1 MIL click is always 37.5% larger than a 1/4 MOA click at the same distance. Source: angular geometry; 0.1 MIL = 0.360" at 100 yd, 1/4 MOA = 0.262" at 100 yd.

Converting between MOA and MIL

One full radian contains 1,000 milliradians. One degree contains 60 minutes of arc. One radian = 180/π degrees = 57.2958°. Therefore:

1 MIL = 57.2958° × 60 min/° / 1000 = 3.4378 MOA ≈ 3.438 MOA

1 MOA = 1 / 3.438 MIL = 0.2909 MIL

To convert MOA → MIL: ÷ 3.438
To convert MIL → MOA: × 3.438

Practical examples:

• Your firing solution calls for 8.5 MOA of elevation. In MIL: 8.5 ÷ 3.438 = 2.47 MIL
• A dope card shows 3.2 MIL of elevation. In MOA: 3.2 × 3.438 = 11.0 MOA
• You read 1.5 MIL of holdover in your reticle. In MOA: 1.5 × 3.438 = 5.16 MOA

In the field you may want a simpler approximation: 1 MIL ≈ 3.44 MOA. The error is 0.06%, which accumulates to less than 0.1" at 1,000 yards — negligible for any practical application.

Worked hold-over calculation

Suppose your ballistic software (or the WeaponTester range) gives you a drop of 36.0 inches at 500 yards for a given load. You need to convert that to a scope correction in both MOA and MIL:

── MOA calculation ──────────────────────────────
1 MOA at 500 yd = 1.047 in × 5 = 5.235 in/MOA
Elevation needed = 36.0 in ÷ 5.235 = 6.88 MOA
Dial on a 1/4 MOA scope: round to 6.75 or 7.00 MOA (27 or 28 clicks)

── MIL calculation ──────────────────────────────
1 MIL at 500 yd = 3.600 in × 5 = 18.00 in/MIL
Elevation needed = 36.0 in ÷ 18.0 = 2.00 MIL
Dial on a 0.1 MIL scope: 2.00 MIL exactly (20 clicks)

The MIL correction resolves to a clean integer here — 2.00 MIL — because 36 inches at 500 yards happens to be a round number in the MIL system. MOA gives 6.88, requiring rounding to the nearest quarter click (6.75 or 7.00). In practice either system will place you within the error margin of your natural point of aim; the math advantage of MIL is most apparent in metric-range environments where drops land on even 0.1 MIL increments more reliably.

The matched-system rule: reticle and turrets must agree

The most consequential decision when selecting an optic is not MOA vs MIL — it is ensuring the reticle subtension marks match the turret click unit. Optics manufacturers produce four common configurations:

• MIL reticle / MIL turrets — the correct tactical/precision setup if you work in MIL
• MOA reticle / MOA turrets — the correct setup if you work in MOA
• MIL reticle / MOA turrets — sold by budget brands; requires multiplying every reticle holdover by 3.438 to dial corrects. Avoid.
• MOA reticle / MIL turrets — rare; equally problematic

A MIL reticle/MOA turret mismatch is not just inconvenient — it is a systematic error source. When you observe a 2.0 MIL holdover in the reticle and dial 2.0 of adjustment on the turret expecting 2.0 MIL, you are actually dialing 2.0 MOA (0.58 MIL). Your intended correction is almost three times larger than what the scope actually moved. This error has caused misses at distances where misses matter.

Which system should you use?

Choose based on your workflow, not your nationality or shooting discipline:

• Choose MIL if: you range targets in meters, work with a spotter who calls corrections in MIL, use metric wind tables, or communicate dope with other MIL-system shooters. PRS competitors increasingly use MIL because range distances are often marked in meters and the base-10 correction math is faster under timer pressure.
• Choose MOA if: you range and think in yards, your existing dope cards are in MOA, or you shoot in an environment where everyone else uses MOA. 1/4 MOA clicks offer slightly finer resolution than 0.1 MIL clicks (0.262" vs 0.360" at 100 yards), which can matter at short-range accuracy work.
• If you're starting fresh: either system is viable. Most long-range and precision rifle communities in the US have moved toward MIL, which means more readily available support, data cards, and coaching in that unit — but this is a preference, not a physics argument.

The one thing that genuinely doesn't matter is the MOA vs MIL choice itself. Both systems resolve to the same angular reality. A 2.47 MIL elevation correction and a 8.49 MOA correction are the same correction. What matters is that your calculation, your reticle, and your turrets all use the same unit.

How WeaponTester outputs corrections

The WeaponTester builder outputs drop and drift corrections in both MOA and MIL simultaneously. The range display shows the full trajectory table with columns for drop in inches, MOA correction, and MIL correction at each distance step. You can match whatever unit your scope uses without any manual conversion.

Trajectory data is produced by our modified point mass integrator, validated against published JBM tables for benchmark loads. For more on how the engine models drag, atmosphere, and spin drift, see how the engine works. For a deep dive on the G1 and G7 drag functions that feed into every trajectory calculation, see G1 vs G7: which to use and why.

Frequently asked questions

Sources

1. Litz, B. Applied Ballistics for Long Range Shooting, 3rd ed. Applied Ballistics LLC, 2015. Primary reference for precision rifle ballistics methodology including angular unit applications in dope systems.
2. JBM Ballistics. Trajectory Calculator documentation. jbmballistics.com. Angular-unit reference used to validate MOA and MIL output from the WeaponTester engine against independent calculations.
3. Nightforce Optics. NX8 and ATACR Series Owner's Manuals. Manufacturer specification source for 1/4 MOA and 0.1 MIL click increment values and their per-distance impact shifts.
4. National Institute of Standards and Technology. SI Units: radian. NIST Special Publication 811. Formal definition of the radian and milliradian, the basis of the MIL angular unit used in ballistics.