Have it measured by a reputable dealer/pro shop. If you're constantly hitting your arm with the string, that might be a clue. I like to have my string touch the end of my nose at full draw, but that's just me.
Have someone measure your draw. Do this by having them measure your arms fully extended to include your finger tips and divide the total of that by 2.5. This will give you a good idea of what your draw is.
what jm said...having your string touch the tip of your nose is a natural position that you'll be able to unconsciously repeat time and time again. One key to accuracy is having the same form over and over...if on one draw you touch your nose, and the other draw you touch your cheek...then you're not aiming down the same barrel =) Your local (reputable) archery store should be able to assist you...most of them even do it for free (mine does) But i think a few signs your draw length is too short is if you're hitting your arm or if you feel "over extended" at full draw...or does your peep sight seem like it could be closer? Here's a picture of what a good draw should look like and where each part of the string should line up with your body =) (hope it helps) 1.) Knuckle meets ear or cheek 2.) Proper kisser location (corner of mouth) 3.) tip of nose touches string below peep site Im thinking that if you're having to stretch your head forward to meet these criteria, you might want to adjust your length.
There are a lot of clues that somebody else can see that you may not be able to. I'm only going to talk about fine tuning becasue I'm assuming you've got a bow that "fits" your draw and we're only talking about 1/2" or less here. If you're way out then these are also going to be way off though. -String naturally touches the tip of your nose when anchored without craning your head around on it. (Draw back with your eyes closed and find a relaxed, natural anchor. Then open your eyes and see where you are.) -Release forearm is parallel to the arrow shaft. (If it's too long your elbow will drop low as you over draw and your forearm will point up.) -When anchored and viewed from behind your release arm should be on plane with the arrow and your elbow should be pointed straight away from the target. (If it's too long you'll pull your elbow beyond this plane and your forearm will point either left or right of the target.) -Bow arm is in a solid, natural position. (If draw is too long your bow elbow will start to come in and you may experience wrist slap.)
http://archeryhistory.com/archerytalk/The_Nuts&Bolts_of_Archery.pdf Archery talk made a PDF that has a lot of good information in it, a lot about telling if your draw is too long or short, a lot of pictures. I think what you're looking for starts on page 32.
One way to get a good idea is to set up a camera with a timer, or have someone take a picture of you at full draw. The camera or person will be perpendicular to the direction you're aiming. If you're leaning back in the picture, you're draw length is likely too long. Also note the other items mentioned above regarding forearm/elbow, etc.
