well the distance from me to the target is 621 but the distance adjusted for the angle is 612. Theoretically with what I'm shooting the difference between those distances is just over 3 inches of drop. The greater the angle the more dramatic. of course it doesn't take into account all the other factors (wind, temp, humidity, etc.) but I like the math and it might help make my ball park guess a little more of an estimate than a guesstimate.