### Milliradians (NATO)

**Abbreviation/Symbol:**

- Mil (NATO)

**Unit of:**

- Angle

**Worldwide use:**

- All NATO countries

**Description:**

A milliradian (also know as a mil) is a unit of angle. There are several distinct definitions but all approximate to a trigonometric milliradian. Mils are generally used in the military for artillery sights.

**Definition:**

A Radian is the angle made by taking the radius of a circle and wrapping it along the circle's edge. Therefore 1 Radian is equal to (180/π) degrees. A standard milliradian is 1/1000 of this value. A NATO Mil, however, is 1/6400 of a circle

**Origin:**

The milliradian ('mil') was first used in the 19th Century by Charles-Marc Dapples, who was a professor at the University of Lausanne. At the beginning of World War I, France started experimenting with using milliradians on artillery sights instead of decigrades (circle/4000). They were used by France alongside decigrades during World War I. The United States, who copied many French artillery practices, also adopted mils.

**Common references:**

- One finger width at an arms length is approximately 30 mils wide. A fist is approx. 150 mils and a spread out hand is approx. 300 mils.

**Usage context:**

The angular mil is used for artillary calculations. One mil translates to approximately one metre at a distance of one thousand metres. The angle is used for calculating either size or range. Where the range is known the angle will give the size, where the size is known then the angle will give the range.

**Multiples:**

- 1 NATO Mil = circle/6400