There is one easy method for finding your bow draw length without a bow. Simply measure your arm span (fingertip to fingertip) and divide the result by 2.5. The result will be pretty accurate.
Did you know?
Olympic swimmer Michael Phelps has a wingspan of 79 to 80 inches which would give him a bow draw using the arm span measurement of 32".
Arm Span Measurement
To measure your wingspan… stand up and hold out your arms either side of you and measure the span of your arms from middle finger tip to middle finger tip, don’t stretch your arms out just hold them up to get a natural measurement.
You might need a friend to help with this (unless you can think of a way to do it by yourself like standing against a wall with ink on your fingertips, making marks and measuring the marked distance maybe?). Ask your friend to measure across your back so that the tape measure is a flat as possible and no extra distance is measured by curving the tape across your chest.
Then take a note of the distance you measure for your wingspan and divide it by 2.5. This is your draw length. If the number is fractional feel free to round it up to the nearest half inch or cm.
Arm span draw length is an approximation it is not a perfect measurement as it relies on the assumption that all humans are proportioned exactly the same. However it is good enough to allow you to purchase your first recurve bow as recurve bows work well with a wide range of draw lengths. You’ll find that your draw length will increase slightly and stabilise after about a year or so of shooting.
ATA Draw Length
The ATA (Archery Trade Association) draw length standard is defined as:
"The distance from the bowstrings nock point to the pivot point of the grip plus 1 3/4 inches (4.5cm) on a correctly drawn bow."
In order to find this measurement you need a bow that will draw easily to your approximate draw length and you need to do this with good technique. Consequently it’s probably best done with an instructor or experienced friend who will have the kit handy. It’s possible to perform this measurement yourself if you have a suitable bow and something called a ‘draw arrow’ which is a long arrow marked with distances that you can draw back, but very few beginners will have access to this type of kit and also won’t draw with correct technique!
Recurve - Drawing Too Short or Too Long?
Bows are designed to be pulled to the ATA draw length so it stands to reason that at this draw length they will be most in tune when shooting. You can see from the ATA specifications diagram for a 28" draw length recurve that once the bow is drawn past the 28" line the level of force increases more quickly, this is called 'stacking'. If the bow is drawn short the potential stored energy isn't as high as it could be.
With a recurve bow there is some margin for error as it will be more forgiving at a wider range of draw lengths than a compound bow.
You can see from the diagram that there is a range within which you can draw a recurve over and above the specified 28". As a general rule of thumb, each inch overdrawn would add somewhere in the region of 2 lbs to the draw weight you will end up holding.
Compound Bow Draw Length
Most compound bows are designed to be shot from the full draw length as they are engineered to draw back so far and then stop, compounds bows can allow for mechanical adjustment to their draw length and are usually specified with a max or min and max draw length. A compound bow is far less forgiving with respect to draw length than a recurve bow, so getting your draw length spot on matters more here.
Peak draw force on a compound bow is achieved part way through the draw cycle so at full draw you're actually holding back LESS force than you will impart onto the arrow than during the let-down phase (when you let go).