Sorry for the OT and polluting a sales thread.
Make yourself a green stick bow. The bow should be the same length and thickness at the grip as the one you are buying. String it up with some strong twine. Notch and Mark up a garden cane with inch marks, draw the cane back like an arrow. Measure off the length to the front of the bow to the back of the arrow.
This will give you a very approximate guide. It will be wrong.
Overdrawing a bow past its rating can stress it causing it to fail. It also adds to the poundage of the bow. Better to under draw as your draw length may increase with practice as you increase in strength and your stance improves.
My draw length changes a bit per bow and per draw weight. Thanks for helping Robbie out MountainM
Robbie its a very hard thing just to pick a draw length without you developing your own form and anchor points first mate and all of these are very personal things. You may pick-up a very light bow and draw it half a dozen times and your DL will be say 28 inches. You then add some weight and strengthen up the "archery only" muscles and your DL will shrink. You may choose a different anchor point such as your corner of your mouth to your cheek, this add another inch.