Mil Relation Formula
Also: Mil Ranging · Ranging Formula
The equation that converts a known target size and its measured mil subtension into distance, providing the math behind reticle-based ranging.
The mil relation formula links a target’s known physical size to the number of mils it covers in the reticle, yielding the range to that target. In practical terms the shooter measures how many mil marks the target spans, then divides the known size by that figure and applies a scaling constant for the chosen units. Because a milliradian subtends a fixed fraction of the distance, the proportion holds at any range.
Accuracy depends entirely on a correct estimate of target height or width and a careful read of the subtension against the reticle. This is the arithmetic that makes reticle ranging possible, and small errors in either the size estimate or the mil count translate directly into proportional errors in the computed distance.