Archery Draw Length Calculator

The AMO estimate divides your arm span in inches by 2.5. An arm span of 70 inches gives 70 / 2.5 = 28.0 inches, a common starting draw length for fitting a bow. The calculator applies the same divisor to whichever measurement you enter.

Yes. Switch to Height mode and the tool divides your height in inches by 2.5, since arm span is close to height for most people. Arm span tracks your actual reach better, so use it when you can measure it and treat height as a backup.

Yes. Toggle the units to cm and type your figure in centimeters. The calculator converts it to inches internally, because draw length is always reported in inches, the standard unit printed on bows and arrows.

No, it is a starting estimate. Your anchor point, release style, grip and shooting form all shift the true number by up to an inch. Confirm the figure at a pro shop with a draw length arrow before you buy a bow.

The Archery Manufacturers Organization chose dividing arm span by 2.5 as a simple, repeatable rule that lands close to the measured draw length for the average adult archer. It is an approximation, not a law of anatomy.

Prefer the arm span figure, because draw length follows your reach more than your standing height. If the two numbers diverge widely, an in-person fitting will be more reliable than either estimate.

The AMO estimate gives one starting number for both. Compound bows lock at a set draw length you must match closely, while recurve archers have a little more range around the estimate. Either way, verify before purchase.

Yes. The calculation runs entirely in your browser and nothing you type is uploaded, so your body measurements never leave your device.

Stand with your back to a wall, raise both arms to shoulder height so they form a straight line, and keep palms facing forward. Have someone measure from the tip of one middle finger to the other, then enter that number.