Some guys use different methods for determining draw length. Some will measure your wingspan then subtract 15" then divide by 2, others will take your wingspan then divide by 2.5. Each gives you a little different number. The best way I've found is to measure from the centerline of your chest out to the line where your hand meets your wrist. This will get you close after that you have to determine what's comfortable and helps YOU shoot the best. I would also read through "the nuts and bolts of archery" over on AT. It should be at the top of the general page. It has a good section on draw length and form.