mil (NATO)
Angleexact by definition
The NATO mil divides a full turn into exactly 6,400 parts, making one mil about 0.0563 degrees or 0.98 milliradians. Artillery and mortar fire control is computed entirely in mils, because at typical ranges one mil is close enough to one metre per kilometre for the gunner's arithmetic to be mental.
Watch out: Three other military mils exist: the Swedish streck at 6,300 to a turn, the former Soviet and Russian system at 6,000, and the true milliradian used on many rifle scopes. A mil-marked reticle and a mil-marked artillery sight may not agree.
| 1 mil | 0.05625 ° |
The 6,400 figure is a deliberate corruption of the 6,283.19 milliradians in a turn, chosen because 6,400 divides evenly into quarters and sixteenths of a circle. Trading 1.9% of accuracy for clean division was the right call when the alternative was long division under fire.