Definition
   
Definition for "mil-dot reticle" : A range-estimating reticle originally designed for use by US Marine snipers in the 1970s. 'Mil' is the shortened form of milliradian, which is the center-to-center distance between dots on the crosshairs. One 'mil' equals approximately 3.6 inches at 100 yards. In order to use a scope with a mil-dot reticle you must first determine if the reticle is in the first or second focal plane. If the reticle is in the first focal plane, you will notice that the reticle will change as the magnification is adjusted. A reticle in the second focal plane is usually designed to perform its range finding capabilities at the highest power, you should verify what power your specific scope is set up to range at if your mil-dot reticle is in the second focal plane. The formula for ranging a target is Height of target (yards) x 1,000 / Height of target (mils) = Range (yards).