The angular 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 angular 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. 1/6400 circle in NATO countries.