Sizing a bow correctly is a critical safety issue.  Your bow is essentially a large wooden spring, and can only be flexed so far without damage.  The longer your draw, the longer the bow required to support it.

Your draw length will be unique to you, and has little to do with your height.  It is dependent upon the length of your arms, width of your shoulders, how you hold your head, and the point to where you draw the string (this is known as your anchor point).

The most common anchor point is to draw until the tip of your middle finger (on the hand holding the string) is in the corner of your mouth.  This provides a reliable reference with respect to your eye, and will generally give the best results for accuracy.

Some archers, particularly those who are accustomed to shooting modern compound bows using a release aid, have a tendency to draw their bow much further, frequently drawing all the way to the corner of their jaw.  We do not recommend this practice.  It places several parts of your anatomy out in front of the string, where they can be slapped (or even torn off) by the bowstring as it leaps forward.  Regardless of where your anchor is, it is critical that your draw length measurement be taken from the anchor point you're going to use when actually drawing your bow.  

To measure your draw length you'll need a measuring device such as a tape measure or yardstick and a narrow shaft (such as an arrow).  Pretend you’re drawing a bow, with one end of your "arrow" between your first two fingers on the drawing hand and the bow hand held horizontal and extended almost directly to your side.  The “arrow” should rest on the web of skin between your index finger and thumb.  Draw the "arrow" back until you reach your anchor point.  Have a friend mark the shaft where it crosses between your thumb and index finger, and measure that distance, rounding up to the nearest inch.  Add an additional inch for the thickness of the bow and you'll have your proper draw length.  We recommend doing this several times until you get a consistent answer.  

Note:  Beginners frequently want to get the shortest bow that they can, reasoning that it will be easier to carry around.  Do NOT make this mistake!  A bow that is too short for you is not safe to use!  A drawn bow stores a great deal of energy, and if an overdrawn bow breaks it can be dangerous.  Get a bow that is sized properly for you.  Also, we do not recommend sharing your bow with others that might have a longer draw length than you do.  Always use good judgement with your bow and it should last you a lifetime.