Draw Length Calculator — Archery Bow Sizing
Find your correct archery draw length from your arm span (wingspan). The AMO/ATA standard formula divides your fingertip-to-fingertip measurement (in inches) by 2.5 — the number bow shops use to fit recurve and compound bows.
cm
Unit
AMO/ATA standard draw length — the measurement bow shops use for fitting
- 1
Convert wingspan to inches
180 cm ÷ 2.54 = 70.87 - 2
Draw length (AMO/ATA)
70.87 in ÷ 2.5 = 28.3
How does this calculator work?
Divide your wingspan (fingertip to fingertip, in inches) by 2.5 to get your AMO draw length. A 180 cm (70.9 in) wingspan gives 70.9 ÷ 2.5 ≈ 28.4 in, rounded to 28.5 in. Round to the nearest half-inch — the standard bow sizing increment. Use this number when talking to bow shops or ordering adjustable compound cams.
Formula
How this is calculated
Draw length is the distance from the bow grip to the nocking point at full draw, measured in inches. Getting it right matters for accuracy, comfort and safety: a draw length that is too short leads to collapsed form and poor arrow flight; one that is too long causes over-extension, string-slap and potential injury. The most widely used method is the AMO/ATA wingspan formula: stand with arms outstretched horizontally, measure fingertip to fingertip, and divide by 2.5. The result is your AMO draw length in inches.
An alternative method sometimes taught by coaches uses (wingspan in inches − 15) ÷ 2, but the ÷ 2.5 formula correlates better with actual measured draw length for most adults and is the industry standard used by bow manufacturers. Results are conventionally rounded to the nearest half-inch because bows and arrow rests are sold in half-inch increments.
Compound bows typically offer an adjustable draw length range of 2–4 inches via rotating modules or cams, making them easier to fit. Recurve bows are fixed-draw and are selected by weight at a specific draw length. If your measurement falls near a half-inch boundary, try both lengths on equipment before purchasing — individual body proportions vary and short in-store testing is more reliable than the formula alone.
Frequently asked questions
Stand against a wall with both arms outstretched horizontally, fingers pointing sideways. Have a helper mark the wall at each fingertip, then measure between the marks with a tape. Alternatively, hold the tape at one fingertip and stretch to the other. Wear fitted clothing — bulky sleeves add length.
The same formula applies to both. Compound bows allow draw-length adjustment (usually ±1–2 inches via cam modules), so you buy a range that includes your measurement. Recurve draw length is chosen to match your measurement, and archers may fine-tune using a longer or shorter arrow or adjusting their anchor point.
For most people, wingspan closely equals height (the basis of the Vitruvian proportions). If you cannot measure wingspan directly, height in inches ÷ 2.5 gives a usable approximation. However, wingspan is always preferred — individual variation of several centimetres is common and can shift the draw length result by 0.5 in.
Also known as
TG we-Calculate Editorial Team. (2026). Draw Length Calculator — Archery Bow Sizing [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/draw-length-calculator
TG we-Calculate Editorial Team. "Draw Length Calculator — Archery Bow Sizing." TG we-Calculate. 2026. https://we-calculate.com/calculator/draw-length-calculator.
TG we-Calculate Editorial Team, "Draw Length Calculator — Archery Bow Sizing," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/draw-length-calculator
@misc{wecalculate_draw_length_calculator, title = {Draw Length Calculator — Archery Bow Sizing}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/draw-length-calculator}}, year = {2026}, note = {TG we-Calculate} }
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