I knew I should have stayed awake in math class! Well their is a method you can experiment with, once you get the string thru the tuner peg, place a hand about mid-way on the fretboard so that your palm is facing the tuner, the string is now is running over the top (thumb&1st finger side) of your hand, this will give an approximate amount of slack to wind on, depending on the width of your hand and the thickness of the string you'll be able to get a rough estimate of how much slack you need, I usaully go about a hand width on the trebles and a little more as I move toward the 6th string and I get about 2-2 1/2 winds per string..................