The wing span method will get you close. streach out your arms as far as you can, have someone measure you fron longest finger to longest finger. For me it is 72 inches. then substract 15, for me that leaves 57 then divide by 2. that gives me 28.5 inches of AMO draw length. Which is right for me. I shoot 28.5 inch AMO draw to 29 inch AMO draw depending on what release I am useing.

AMO draw length is distance from the string at full draw to the throat of the grip plus 1 3/4 inches. All the bows are rated with AMO draw length. supposed to be anyway..