The wingspan method is usually a good starting point to help determine draw length. A person's physical characteristics...finger length, hand length, shoulder width, etc... also all do play a part in "fine tuning" that initial estimate.
Here is a brief wingspan chart to make things easier for those just starting.
How to measure your wingspan:
1) Lean against a wall, standing as close to the wall as possible with back flat.
2) Extend your arms and fingers out as far as possible
3) Have someone make a pencil mark at the end of both your fingers tips
4) Measure this distance
This is your wingspan. Find this number in the chart below to find its matching Draw Length. (For example, a wingspan of 67" would be a draw length of 26")
Wingspan Draw Length
(inches) (inches)
63 24
64 24 1/2
65 25
66 25 1/2
67-----------------------------------------------26
68 26 1/2
69 27
70 27 1/2
71 28
72 28 1/2
73 29
74 29 1/2
75 30
76 30 1/2
77 31
78 31 1/2
*** The Most Common Draw Length is 29 inches.