black recurve bow

How to Measure a Bow String (Our 2 Methods) 

Bowstrings come in a variety of different lengths. Knowing how to measure a bowstring is an important step in purchasing the correct length. We will go through the process below. 

There are two basic ways you can figure out your bowstring length. The first method is more direct and gives you insight into how the string length is determined. The second method is more direct and takes much less time. 

You can measure your bowstring length following these steps; 

  1. Place your bow on a bow press 
  2. Make a loop with a string and place the loop over one of the axels 
  3. Wound the string around the bow like a bowstring 
  4. Pull the string towards the other axel compressing the bow 
  5. Wind the string around the other axel when the bow is compressed 
  6. Mark the length of the string you needed to wound around and compress the bow 
  7. Measure the length of the string, and this is your bowstring length 

Bow String Creates Draw Length 

The draw length is the measure of how far the rare end of an arrow can get from the center of the bow when you draw. If the bowstring is too long, there will not be enough weight in the draw to shoot the arrow with much force. If the string is too short, the bow will be too tense, and it would make it harder to draw. Here’s more information on how to measure draw length on a bow.

How Long Should the Bow String Be? 

There is a sweet spot for the bowstring length that maximizes the draw weight while still making it possible to draw an arrow. Since different people can afford to apply different amounts of force, the actual ideal string length may vary a little from person to person. But the variation is tiny and the rules discussed here to determine the bowstring length are probably valid for you. 

There may also be some variations in the ideal string length depending on your manufacturer, and you can determine the string length that is ideal for your bow by measuring the length of the string that came with the bow. However, if you don’t have the original string, you can still use this article to figure out the right string length. This is because almost all manufacturers follow the AMO system, and bows of the same length from different manufacturers also have the same string length. (1)

And to understand more about the length of a bow string—here’s the recurve bow string length chart that would make it easier for you to follow through.

First Method: Manually Measuring your Bow 

It is much easier to determine the string length of a recurve bow than of a compound bow. If you have a compound bow, you will require the following extra equipment. 

  • A tape measure 
  • A marker 
  • A long string or twine 
  • A bow press 

You will measure the total length of the string from the top axle to the bottom cam, then to the upper cam, and eventually to the bottom axle. 

The string or twine should be strong enough that it does not break under 60-70 pounds of force, but it also has to be thin enough that you can make a loop with it and tie it to the axels on the cams. 

The marker should be suitable for the string. If a normal marker is not able to mark the string, you may need to use a permanent marker. 

The bow press will help you compress while you measure the bow length, but it will also help you string and unstring your bow. If you don’t have a bow press, we would suggest you invest in one. (2)

Step 1: Place the Compound Bow in a Bow Press 

In order to simulate drawing, you’ll have to place the compound bow in a bow press. The raiser should be facing you. Alternatively, you could ask a friend to compress the bow. But you can’t compress the bow yourself while measuring the bowstring length. Once the compound bow is placed on the bowing process, tighten the vice grip of the bow press. The string side of the bow should be facing you. 

Step 2: Make a Loop on One End

Take your string a make a loop on one end. Make sure the loop is big and firm enough. It should not be a tightening loop. An easy way to do this is to tie a knot but not tighten it all the way. When the knot is still a big loop, as shown in the picture, tie another knot on top of it and tighten it. Tie a third knot, and your fixed loop is ready. This is certainly not the cleanest way to get this loop, but it is quite easy and adequate for our purpose. 

 

Step 3: Place this Loop Over the Pin 

Now place this loop over the axle or the pin on the right cam such that it is hooked in place tightly as a bowstring would. Take the string to the left cam and wind it around. Now wind it around the right cam. This string would be wound the same way a bowstring is wound.

Step 4: Pull the String Towards the Other Cam 

Now compress the bow and pull the string towards the other cam. In order to get an accurate measure of the string length, the bow should be compressed as much as it is when it is strung. Compressing the bow and pulling the string, wind it around the left axel or the pin. These steps are quite intuitive since you’re just winding the string like a bowstring.

Step 5: Mark the String at the End 

Use your marker to mark the string right where it meets the axel. The length of the string from the loop on the right axel to this mark is the length of your bowstring.

Step 6: Use a Tape Measure to Measure the Length 

Unwind and unhook the rope and use a tape measure to measure the length of this string from the loop to the mark. This is the length your bowstring should be. You can buy a reserve bowstring of this length and string it.

Second Method: Using the AMO Length 

Archery Manufacturers Organization or AMO is a set of standards for bow lengths, draw weights, string lengths, and other measurements for all the major kinds of bows that almost all the bow manufacturers follow. AMO also has standards for the relationships between these measurements. This can allow you to determine one measurement if you know the others. For example, if you know your bow length and your draw weight, you can use the AMO table to determine exactly what the string length should be. 

If you already know your AMO length or if your bow has its AMO length printed on it, you’re in luck because you don’t need to follow the method described before. You can instantly know your bowstring length by reading the AMO label. The AMO label has information about your bow, including the draw weight and bowstring length. For a compound bow with a craw weight of 50 pounds, the string length would be around 58 inches. If your bow AMO label does not list the string label, you can use a standard AMO table to determine your bowstring length based on the draw weight of your bow given on the AMO label. 

If neither of the described methods is accessible to you could contact the manufacturer of your bow and give them your model number or send them a picture of your bow. Manufacturers have data about all their bows in their archives. But we would suggest trying the first method at least once if you’re serious about archery. It will help you gain insight into what determines your bow length and into how your compound bow works in general.

A bow press is definitely worth investing your money in as it saves a lot of time. You will probably be stringing and unstringing your bow regularly, and a bow press will make it a much easier job. 






References
(1) manufacturer – https://www.britannica.com/technology/manufacturing
(2) invest – https://www.nerdwallet.com/article/investing/how-to-invest-money