MOA and MRAD can be tricky I guess.
It never changes and is a constant. Do not confuse the TWO they are very different. Why did I convert MRAD to inches when MM are the standard unit. Because we still measure in inches and still call MOA groups (I don't like it either)...
Milliradian usage is not complicated, though it may seem so at first.
1000radians = milliradian
1 milliradian = 1000radians
Basically, one “mil” equals 1 unit at 1000 units of distance.
So a 1” object will occupy 1 mil of space on the reticle when it is 1000 inches away.
3.6” at 3600 inches (100 yards)
1 foot at 1000 feet
1 yards at 1000 yards
1 meter at 1000 meters
For those thinking in terms of Minute-of-Angle (MOA),
1 mil = 3.438 MOA.
I still get asked this very frequently and was just PM'd about how to know these values. SEE THE MATH PORTION AT THE BOTTOM
I hope I didn't make any mistakes.