How to Determine the Correct Bowstring Length for Your Compound, Recurve, or Longbow

A quick guide to determining the correct bowstring length for your bow

Have you ever needed to replace a bowstring, only to realize you don't know the correct bowstring length your bow nees? With over 38,000 sporting goods stores in the U.S. most of us have probably left that determination up to our favorite store or manufacturer. Even though many bows come with strings ready to shoot it is helpful to know a few simple tricks in case you ever want to replace your own bowstring or simply put a bowstring on a stringless bow.

To determine the correct bowstring length for your bow, you should:
1. Use AMO Length to Determine Correct Bowstring Length 
     or...
2. Manually Measure Your Bow

1. Using AMO Length to Determine Correct Bowstring Length

AMO is short for Archery Manufacturers and Merchants Organization. Typically a bow will be marked with the AMO which refers to the standardized length of the bow This is especially helpful in regards to determining bowstring length on a recurve or longbow. To help illustrate how bowstring length can be measured using the AMO please refer to this image: 

 The AMO represents the length of the bow from tip to tip, and the generally accepted rule among archers is the correct bowstring length on a longbow is 3" less than the AMO, and on a recurve it is 4" less the AMO. So in this example of a 58" AMO, if this were a longbow we would need a 55” bowstring length, or a 54” bowstring length if this were a recurve. An important reminder here is that many shops actually sell bowstring lengths according to the AMO, so as in this case a 58” AMO would require a 58” AMO bowstring. So it is important to clarify with your sporting goods store on whether they sell bowstring length by the AMO or the actual length needed. Compound bows will typically have a label that includes information like weight, string length, cable, and draw. In most cases what is listed on the label will indeed be the bowstring length that you need for that particular bow.

Here is an example of a label found on my Martin bow:

So as you can see, my compound bow requires a 58" string. 

2. Manually Measure Your Bow

Sometimes the AMO or label is missing on the bow, and you are left to figuring out the correct bowstring length from scratch. Here I have a Paul Bunyan Recurve, but it only provides the draw weight so I must manually figure out the string length: 

Don’t worry - it's easy! To find the correct bowstring length on a recurve or longbow you will need a tape measure. Using the tape, measure along the curve of the bow limbs from string groove to string groove, this will give you the correct string length. You can also measure the bow from tip to tip to find the AMO and then subtract accordingly depending on the make of the bow. Remember to measure across the face of the bow limbs and to not measure into the curve of the handle.

Bow Length and String Length Diagram:
 
Moving from traditional bows to compound bows the process becomes a little bit trickier in regards to measuring. The AMO bow string length standard suggests that compound string length be determined by applying 100 lbs. of tension and measuring from outside of pin to outside of pin with your string. A way to do this yourself is to put the bow in a bow press, and taking a piece of string make a loop and place it on the peg found on the cam and then wrap it around the cams and bring the string to the other peg on the opposite side of the bow.

Holding the cams so that they look similar to when the bow is actually strung you can adjust the brace height to ensure a realistic feel and visual for how the bow will look fully strung. From there you can take a marker and mark the string at the peg opposite of the loop. Finally you can measure the length of the string from your loop to the mark you made, and this should give you the proper length needed for your compound bow. This process is much easier with a helper, happy stringing!

NEXT: BOW STABILIZERS - EVERYTHING YOU NEED TO KNOW ABOUT THIS MYSTERIOUS BOW ACCESSORY

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