Ape Index Calculator: Arm Span vs Height (Difference and Ratio)
Find your ape index from arm span and height, as a difference (in or cm) and as a ratio, with a plain reading and a comparison with US Army averages, NBA players and elite athletes.
How it works
Ape index (difference) = arm span − height · Ape index (ratio) = arm span ÷ height · Typical arm span ≈ height × 1.033 (US Army men, 2012)
The ape index compares your arm span (fingertip to fingertip, arms straight out to the sides) with your height. Climbers usually quote it as a difference, such as “+2 inches” or “+5 cm”, while sports scientists use the ratio, where 1.000 means your span equals your height, the proportion in Leonardo da Vinci’s Vitruvian Man. This calculator gives both, a plain-language reading and a table that places you next to population averages and well-known athletes, scaled to your own height. Most adults are not exactly 1.000: the 2012 US Army anthropometric survey found an average ratio of about 1.033 for men, and NBA players average about 1.063. A positive ape index can help in climbing, boxing and MMA (where arm span is quoted as reach), swimming and basketball, but studies of climbers and fighters show it is far from decisive; technique and strength matter more. Measure carefully: a 1-inch error in either number moves the ratio by about 0.015. There is no other ape index tool on this site; for body proportions related to health, see the waist-to-height ratio calculator.
Worked example
You are 5 ft 10 in (70 in) tall with a 72 in (6 ft 0 in) arm span. Ape index = 72 − 70 = +2.0 in, and the ratio is 72 ÷ 70 = 1.029, a positive ape index: your span is 2.9% longer than your height. The typical span for a man of your height at the US Army average ratio is 70 × 1.033 = 72.3 in, so your span is 0.3 in shorter than that average.
Sources: Wikipedia: Ape index (definition, US Army survey averages, NBA average, athlete examples) · Omni Calculator: Ape index (ratio and difference forms)
Frequently asked questions
What is a good ape index?
Anything above zero (a ratio above 1.0) means your arms span more than your height, which is an advantage in reach sports. Most men are around +2 in (ratio about 1.03); +4 in or more (ratio above 1.05) is long, and many elite basketball players and fighters are above 1.06. A negative ape index does not stop anyone from climbing or fighting well.
How do I measure my arm span?
Stand with your back flat against a wall, arms straight out to the sides at shoulder height and palms facing forward. Have someone mark the tips of your middle fingers, then measure between the marks. Measure your height barefoot against the same wall.
Is wingspan the same as reach?
In boxing and MMA, “reach” is usually measured exactly like arm span, fingertip to fingertip. In basketball, standing reach is different: it is how high you can touch with one arm up, which depends on height, shoulder width and arm length together.
What is the average ape index?
For men in the US Army surveys the average arm span was 71.42 in against a height of 69.14 in (2012), a ratio of 1.033 or about +2.3 in. Women tend to be slightly lower. Leonardo’s Vitruvian Man assumes exactly 1.0.
Does ape index matter for climbing?
It helps reach distant holds, but studies disagree on how much. Some found it among the best predictors of climbing grade, others found no significant effect once training was considered, and several top climbers have a negative ape index.
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This calculator is for educational purposes. Double-check important results before acting on them.