As a general rule of thumb the string length needed for a recurve will be 4" shorter than AMO length for dacron or 3" shorter for low stretch 'fast flight' materials or longbow string. With that said the AMO standards aren't always followed. If your bow does not have a string or you want to double check the measurment by measuring the bow unstrung. To do so measure from string groove to string groove in a straight line along the belly of the bow.
Bowstrings are measured at the industry standard of 100lbs of tension so please order accordingly. If measuring hand tight the bowstring will measure upto 1" shorter depending on bow string material. Please email with any questions prior to ordering.