MOA vs. MIL vs. Degrees
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MOA, MIL, and degrees are three ways to describe an angle. When a scope or a picatinny rail incorporates tilt or adjustment, it's always in one of these systems. The difference sounds small, but it changes both calculations and practical handling in the field.
The basics
A circle consists of 360 degrees. Each degree can be divided into 60 arcminutes, where one arcminute is one MOA (Minute of Angle). MIL is a completely different unit – often abbreviated as mrad – and comes from military calculations, where a circle is divided into 6,400 milliradians.
| Unit | Divisions in the circle | Typical click |
|---|---|---|
| Degrees | 360 | Rarely used in scopes |
| MOA | 21,600 (60 × 360) | 1/4 MOA per click |
| MIL (mrad) | 6,400 | 0.1 MIL per click |
What does it correspond to on the target?
At 100 m, 1 MOA covers approximately 29 mm. At the same distance, 1 MIL covers approximately 100 mm. At 300 m, 1 MOA therefore covers approximately 87 mm, while 1 MIL covers approximately 300 mm. MOA thus feels "finer" and MIL "coarser", but both systems can provide similar adjustment options because the click size is different.
Practical differences
- Zeroing: With 1/4 MOA clicks, the point of impact moves approximately 7.3 mm per click at 100 m. With 0.1 MIL clicks, the point of impact moves approximately 10 mm per click at 100 m.
- Hold-over: MIL is easy to calculate with because it corresponds directly to metric distances. MOA is simple if you already think in arcminutes per distance.
- Compatibility: If the scope has a MIL reticle, the turrets should also be MIL. The same applies to MOA. A mixed setup is confusing in practice.
Conversion between systems
Rules of thumb that are sufficient in the field:
- 1 MIL ≈ 3.438 MOA
- 1 MOA ≈ 0.291 MIL
- 1 degree = 60 MOA
What does this have to do with the picatinny rail?
A picatinny rail can have a built-in cant, indicated in MOA – typically 20, 25, or 30 MOA. The cant shifts the scope's elevation range, leaving more elevation adjustment for long distances. If you want to see how the cant is used in practice, you can read more about MOA cant on picatinny rails and picatinny rail for long-range shooting.
Although the rail is usually specified in MOA, the scope is not necessarily. It therefore makes sense to check the scope's unit before choosing a cant.
Which system is best?
For many hunting purposes, the choice is less important than choosing one system and sticking with it. MOA is common on American hunting scopes and is often used in classic rifle hunting. MIL is widespread among long-range shooters, tactical shooters, and in military systems. Many find that MIL is faster to calculate with, while MOA feels intuitive if you are used to it.
When does it mix with rail selection?
If you plan to shoot at longer distances than normal hunting ranges, you should compare the scope's elevation range with your typical distance. If elevation is lacking, you usually gain the most by choosing a rail with MOA cant. This consideration is briefly covered in the guide to finding the right picatinny rail, and the mounting choice itself is in choosing a scope mount.
Common misconceptions
- MOA is not American and MIL is not European. Both units are used worldwide, and the choice depends more on the scope manufacturer and application.
- 1 MOA is not exactly 1 inch at 100 yards. It's close, but not exact – true MOA is 1.047 inches.
- MIL is not the same as "military". MIL is an angular unit, and it is also used in civilian sport shooting.
Short checklist
- Use the same unit on reticle and turrets.
- Know your distance before choosing an MOA cant on the rail.
- Consider how many clicks will be used at your typical distances – this guides the choice more than the system name.
- Read up on return to zero if you frequently switch between optics.
For a basic understanding of the rail itself, see the article on what a picatinny rail is, and the dimensions can be found in picatinny rail measurements and dimensions.
How angle translates to distance
The basic principle is that angles grow linearly with distance. An angle of 1 MOA covers approximately 29 mm at 100 m, approximately 58 mm at 200 m, and approximately 87 mm at 300 m. This means that a small error in zeroing at short distances becomes noticeably larger at long distances. This is one of the reasons why precision shooting requires a scope with sufficient click fineness and a reliable zero.
In the MIL system, the calculation is simpler for metric distances. 0.1 MIL covers approximately 10 mm at 100 m. At 600 m, the same 0.1 MIL covers approximately 60 mm. It is linear, and this makes hold-over calculation quick: if you know the target is one meter tall and it spans 1 MIL in the scope, then it is 1,000 m away.
A calculation example from the field
Assume you are shooting a 6.5 Creedmoor at 300 m and your ammunition requires 4.5 MOA elevation correction. With a scope that has 1/4 MOA clicks, you need to adjust 18 clicks up. With the same distance and 1.3 MIL correction on a MIL scope with 0.1 MIL clicks, you need to adjust 13 clicks up.
Both yield precisely the same point of impact on the target. The difference is only in how you calculate and how many clicks you need to move. With practice, one system becomes as fast as the other.
When scope and turret must match
A mixed setup – e.g., a MIL reticle and MOA turrets – is a typical source of errors. When you see a correction in the reticle and need to move the turrets accordingly, it is practical for the units to be the same. This is one of the first things that should be checked when buying a scope: does it say MOA or MIL on both the reticle and the turrets?
Most modern scopes are built with matching units, but it is worth verifying. In older or cheaper scopes, mixtures have occurred.
A couple of practical notes
- A scope with 1/2 MOA clicks is too coarse for long range, but can be sufficient for classic hunting.
- A scope with 0.1 MIL clicks is a typical standard on modern tactical scopes and works well for long range.
- 1/8 MOA clicks are found on dedicated precision scopes but are overkill for general use.
Angles and the rail itself
The primary way angular cant factors into rail selection is as MOA cant. If you shoot beyond normal hunting distances and run out of elevation, an MOA cant is typically the simplest solution. Therefore, 20 and 30 MOA are common choices for long-range rails. On a flat rail, the Mechanical Zero is centrally located, which is optimal for normal hunting distances but limiting at long ranges.