A really general rule is that your arrows will be the same length as your draw length (29 inches in my case). However, seasoned archers really want to dial in their setups (based on spine and also arrow weight), so that length might vary depending on the arrow rest. When in doubt, make a quick trip to your local pro shop and have them measure your arrows. Just be sure to buy something when your there. These guys are trying to make a living, too!