Buying and setting up a new compound bow can be tough. Learning all the ins and outs of the features, ATA length, bar height, cams, single cam, double cam…the list goes on and on. The first thing you need to know before buying a new bow is your proper Draw Length.
Knowing what your proper draw length is, is very important so that the bow is optimized for you when you are at full draw with a bow. You don’t want to pull the string back and have it too short and you definitely don’t want it to be too long. Plus, you must know your draw length when buying a new bow because every bow has specific draw length limits. You must know your correct draw length before you can buy.
The calculator below will get you close. Just remember that even if you measure perfectly, you may have to adjust the draw length on your bow slightly. In most cases, it is recommended that you go to your local Archery Pro Shop and have an expert there set things up for you.
The Draw Length Formula
The calculator here uses the formula: wingspan/2.5 (wingspan is measured in inches)
This formula tends to get closer to the exact draw length for most people as you don’t want to have your anchor point too far back towards your ear. The anchor point for your draw should be closer to the corner of your mouth, mid-cheek on your shooting side.
This formula tends to provide a little extra length and some people end up rounding it down. For most, the formula listed here will give them exactly what they need. It is very dependent on your individual wingspan measurements. The form below will give the exact draw length number, but you will have to round to the nearest half-inch.
Bows usually advertise different allocations of draw lengths. For example, a bow may advertise a range of 26″ to 30″ in half-inch increments. Knowing what your specific draw length is will allow you to know what bows are available in your specific length. Either way, it is always important to check this at your local Archery Shop to ensure the best fit possible before you buy and then tune your bow.
Please remember that the release aid you use will impact your draw length. A normal mechanical release will normally work just fine with the calculator here. If you use a finger-style release where your trigger is engaged with your thumb instead of your trigger finger; you will need to subtract .5″ from your draw length total when using the calculator below.
How to Calculate Your Draw Length
Calculating your draw length is easy and only requires a few steps. Follow the steps below and you will be ready to buy and set up your new Compound Bow!
Measure Your Wingspan
Stand with your back flat against a wall and stretch your arms out to your sides, with your hands and fingers extended (as shown in the picture above). Then measure the distance, in inches, from the tip of your middle finger on one hand to the tip of your middle finger on the other. This will measure your total wingspan in inches.
Calculate Base Draw Length
Take the total wingspan measurement from Step 1 (in inches) and divide that number by 2.5. For example, my total wingspan is 68 inches. 68/2.5 = 27.2. This is then rounded to 27. My base draw length is now estimated to be 27″.
Always round to the nearest .5″.
Adjust Draw Length Based on Release Aid
If you are using a normal mechanical release aid to shoot your bow, your draw length is what was calculated above in Step 2. If you are using a finger-style release as shown in the picture here, then you will need to Subtract .5″ from your total draw length. For example, my draw length was calculated at 27″ in Step 2. If I am using a finger-style release, my draw length would be calculated as 26.5″ (27 – .5 = 26.5).
Always work with an Archery Professional to ensure your draw length is sized perfectly to you and your release aid type. Rounding can change your best possible draw length slightly depending on your body type.
Now you are ready to buy or set up your new bow to your personal draw length.
To calculate your draw length fast, enter your wingspan measurement (in inches) into the calculator below now.
How do I find the draw length of a compound bow?
If you have a compound bow and do not know what the current draw length is set to, remember that the draw length on a bow is measured from the nocking point on the string to the throat of the grip (the deepest part of the grip) plus 1.75 inches when at full draw. In addition, some bows have settings displayed on the bow’s cams. This is sometimes displayed in single digits and may vary from bow to bow.
Does draw length affect arrow speed?
Yes, your arrow’s speed is increased with every half-inch of draw length and decreased as draw length decreases. This is due to the bow not being drawn to its fully optimized length. If your draw length matches the bow’s maximum, then this is not a factor for that specific bow. To see all the factors that affect arrow speed, check out the Arrow Speed, Kinetic Energy, and Momentum calculator here.
Why is knowing my draw length important?
Compound bows are sold in specific draw lengths. These are set so they can fit your specific measurements and allow for a perfect length at full draw and maximize your ability to shoot the bow accurately. This is all critical when choosing or buying a bow.