This will help you figure out what you need. Usually the bow string length for a recurve is the AMO less 4" (a 54" AMO bow would use a 50" string). But you have to be careful because some bowstrings are sold by AMO. Which means that if the label on the string says 54" AMO the string is probably 50" in length. Best to take a tape measure with you and measure the string itself. If your AMO is not marked on your bow, measure from tip to tip (not nock to nock)


https://asklancelot.com/how-to-determine-string-lenght/