Ape Index Calculator

Example: 175 cm tall, 180 cm span: +5.0 cm, ratio 1.029

Is your arm span long for your height? Enter both measurements to get your ape index as a difference and a ratio, your percentile among more than 6,000 measured adults, and a side-by-side with Michael Phelps, NBA Draft Combine record holders and a gorilla.

Last reviewed by SparkCalc editorial team · October 2026

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Arm span

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Where you fall among measured adults

Ape Index

Span to Height Ratio

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Proportion

Typical Span at Your Height

Closest Listed Match

Your Span as a Gorilla

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How to use this calculator

Choose metric or imperial units.
Measure your height barefoot against a wall and enter it.
Stretch your arms straight out at shoulder height, have someone measure middle fingertip to middle fingertip, and enter the span.
Pick men or women to choose which measured sample sets your percentile.
Read your ape index and ratio, then open Famous Spans and Sports for context.

How We Calculate This

Ape index (difference) = arm span − height. Ratio = arm span ÷ height. Percentiles come from the ANSUR II public working databases (4,082 men and 1,986 women aged 17 to 58, measured in 2012): the ratio was computed for every subject from the published span and stature, and the calculator interpolates between the 1st, 5th, 10th and every fifth percentile up to the 99th. Results outside that range are reported as below the 1st or above the 99th percentile. Typical span at your height uses the sample mean ratio. Athlete rows use official NBA Draft Combine barefoot height and wingspan, the UFC listed height and reach, and published figures for Michael Phelps. The gorilla row uses the Smithsonian National Zoo figures for a standing adult male western lowland gorilla (6 ft tall, 8 ft span).

Methodology last reviewed: October 2026. How SparkCalc works

Sources: Gordon et al. 2015: 2012 Anthropometric Survey of U.S. Army Personnel (ANSUR II), public data · NBA.com: NBA Draft Combine, largest wingspans · UFC: Jon Jones athlete profile · Biography.com: Why Michael Phelps Has the Perfect Body for Swimming · Smithsonian's National Zoo: Western lowland gorilla · Mermier et al. 2000: Physiological and anthropometric determinants of sport climbing performance · Watts et al. 2003: Anthropometry of young competitive sport rock climbers · Lavoie and Montpetit 1986: Applied physiology of swimming · Kirk 2016: Does stature or wingspan length have a positive effect on competitor rankings in elite MMA? · Epstein: The Sports Gene (2014), pp. 134 to 135

Why most people have a positive ape index

The Vitruvian idea that arm span equals height is close but slightly short for most adults. In ANSUR II, half of the men had a ratio above 1.031 and half of the women above 1.018. A span a few centimetres longer than your height is ordinary; a negative index is the less common result, found in about 10% of the men and 26% of the women.

What changes at the extremes

The athletes in the comparison table are selected for reach. Doug Wrenn measured 6 ft 5.75 in barefoot with a 7 ft 7.5 in span at the 2003 NBA Draft Combine, a ratio of 1.18, far beyond the 99th percentile of the Army sample (1.10 for men). A standing male gorilla, at 6 ft tall with an 8 ft span, sits at 1.33.

How much measurement error matters

The ape index is a small difference between two large numbers, so careful measuring matters. Standing reach, shoulder flexibility and whether the arms are truly level all shift the result. Measure twice against a wall and use the average.

Arm span to height ratio by percentile

ANSUR II measured sample, ratio of arm span to stature.

Arm span to height ratio by percentile
Percentile	Men	Women
5th	0.991	0.975
25th	1.014	0.999
50th (median)	1.031	1.018
75th	1.050	1.038
95th	1.081	1.072
99th	1.104	1.094

4,082 men and 1,986 women aged 17 to 58, measured in 2012.

Key terms

Ape index: Arm span minus height, or arm span divided by height. Positive (or above 1.00) means your span is longer than you are tall.
Arm span (wingspan): The distance between the middle fingertips with both arms stretched straight out to the sides.
Stature: Standing height measured barefoot, the height value used in anthropometric surveys.
Percentile: The share of the measured sample with a lower ratio than yours. The 75th percentile means a longer relative span than 75% of the sample.

Frequently Asked Questions

What is the ape index?

The ape index compares arm span with height. Climbers usually quote it as a difference (span minus height, so +5 cm means your span is 5 cm longer than you are tall). Others quote it as a ratio (span divided by height, so 1.03). A ratio of 1.00 means span equals height.

What is a normal ape index?

Most adults have a span slightly longer than their height. In the 2012 US Army anthropometric survey (ANSUR II), men averaged a ratio of 1.033, about +5.8 cm, and women 1.020, about +3.2 cm. About 89% of the men and 74% of the women had a span longer than their height.

How do I measure my arm span accurately?

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 tip of each middle finger and measure between the marks. Measure height barefoot against the same wall. A 1 cm error in either number moves the ratio by about 0.006.

Does a positive ape index make you a better climber?

It helps with reach between holds, but the research is mixed. In one study of sport climbers, trainable factors such as strength and endurance explained 58.9% of the variation in performance, while body dimensions explained 0.3%. Training matters far more than proportions.

Why do NBA players have such long wingspans?

Selection. Reach helps with rebounds, blocks and contesting shots, so the league collects people with long arms. NBA players average a ratio of about 1.06. At the Draft Combine, Mo Bamba measured 6 ft 11.25 in barefoot with a 7 ft 10 in span, a ratio of 1.13.

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ANSUR II measured US Army personnel, so its percentiles describe that sample rather than every population. Athlete figures are published measurements and may differ from other sources. This calculator is for curiosity and sport context, not medical or genetic assessment; consult a healthcare professional if you have concerns about growth or body proportions.

References