The mil (in full, angular mil) is a unit of angular measure. This article is about angles in geometry. ...

Origin of the name

All versions of the mil are approximately the same size as a milliradian. The radian (symbol: rad) is the SI unit of plane angle. ...

Use

The mil is commonly used by military organisations. Its relationship to the radian gives rise to the handy property that object of size S that subtends an angle A mils is at a distance D = 1000*S/A. Alternatively, if the distance is known, we can determine the size of an object by S = A*D/1000. The practical form of this that is easy to remember is: 1 mil at 1 km is about 1 metre. Another example: 100 mils at 2 km is about 200 metres.

However, military mils are fixed angles not based on the above formula.

In the general case, where neither the distance nor the object size is known, the formulae may be of little use. In practice, sizes of observed objects are known with reasonable accuracy since they are often people, buildings and vehicles. Using the formulae, distances of the objects can be readily calculated without a calculator. In military terms, distances are of course essential for artillery bombardments and estimations of journey times. Historically, artillery refers to any engine used for the discharge of projectiles during war. ...

Many telescopic sights used on rifles have reticles that are marked in mils, and these are generally called mil dot scopes. The mil dots serve two purposes, range estimation and trajectory correction. By determining how many mils an object of known size subtends, the distance to that object can be estimated with a fair degree of accuracy. Once the distance is know, the drop of the bullet at that range (see external ballistics), converted back into mils, can be used to adjust the aiming point. Generally mil dot scopes have both horizontal and vertical crosshairs marked; the horizontal and vertical marks are used for range estimation and the vertical marks for bullet drop compensation. Skilled shooters, however, can also use the horizontal dots to compensate for bullet drift due to wind. Mil dot scopes are most suited for long shots under uncertain conditions, such as those encountered by military snipers and varmint hunters. In both of those cases, the range to the target is not fixed and shots are taken at extreme ranges, so accurate compensation for bullet drop is required. View through a 4x rifle scope A telescopic sight, commonly referred to as a scope, is a device used to give an accurate point of aim for a firearm. ... A rifle is any long gun which has a rifled barrel. ... As used in photolithography, a photomask is typically an optically transparent fused quartz blank imprinted with a pattern defined with chrome metal. ... External ballistics is the part of ballistics that refers to the behavior of a bullet after it exits the barrel and before it hits the target. ... The traditional definition of a sniper is an infantry soldier especially skilled in field craft and marksmanship, who kills selected enemies from concealment with a rifle at long distances. ... Varmint rifle is an American English term for a relatively small-caliber firearm (or even a high-powered air gun) primarily used for hunting varmints—such as coyotes and smaller. ...

The three definitions of the mil

There are 2000×pi milliradians in a circle. So a milliradian is just over 1/6283 circle. Each of the definitions of mil are similar to that value but are easier to divide into many parts. Lower-case pi The mathematical constant Ï€ is a real number which is defined as the ratio of a circles circumference (Greek περιφέρεια, periphery) to its diameter in Euclidean geometry, and which is in common use in mathematics, physics, and engineering. ...

• 1/6400 circle in NATO countries.
• 1/6000 circle in the Soviet Union
• 1/6300 circle in Sweden. The Swedish term for this is streck literally "line". Sweden has not been part of NATO or the Warsaw Pact