Enter your arm span (fingertip to fingertip) and height to calculate your Ape Index — both the subtraction method (arm span minus height) and the ratio method (arm span divided by height). Choose your preferred unit system and instantly see whether your ape index is negative, neutral, or positive, and what that means for sports like climbing.
Ape Index (Subtraction Method)
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Ape Index (Ratio Method)
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Category
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Arm Span
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Height
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The Ape Index (also called the Ape Ratio) is a measure that compares your arm span (wingspan) to your height. It can be expressed as a ratio (arm span ÷ height) or as a simple subtraction (arm span − height). A person with equal arm span and height has a ratio of 1.0 and a subtraction index of 0, which is considered perfectly average.
There are two common methods. The subtraction method subtracts your height from your arm span (e.g. 180 cm arm span − 175 cm height = +5 cm). The ratio method divides arm span by height (e.g. 180 ÷ 175 = 1.029). Both convey the same information — whether your arms are proportionally longer or shorter than your body.
For most people, an ape index near 0 (subtraction) or 1.0 (ratio) is perfectly normal. A positive ape index means your arms are longer than your height, which can be advantageous in sports like climbing, swimming, and boxing. A negative ape index means your arms are shorter relative to your height, which may suit sports requiring compact leverage such as gymnastics.
A positive ape index is often cited as beneficial in climbing because longer arms can reach holds that shorter-armed climbers cannot. However, research and elite climbers suggest that finger strength and technique are far more predictive of climbing performance than ape index. Adam Ondra, widely regarded as the greatest climber alive, has an ape index of just +1 cm.
Stand with your back against a flat wall and extend both arms out to your sides, keeping them parallel to the floor. Have someone mark the wall at each fingertip, then measure the distance between the two marks. Make sure your fingers are fully extended and your arms are truly horizontal for the most accurate reading.
The average person has an ape index very close to 0 using the subtraction method, or approximately 1.0 using the ratio method, meaning arm span and height are roughly equal. Small deviations of ±5 cm or ±0.03 in ratio terms are entirely common and within the normal range.
A longer arm span relative to height can be advantageous in rock climbing (reaching distant holds), swimming (greater pull through the water), basketball (wider defensive and passing range), boxing (keeping opponents at distance), and volleyball (wider blocking and spiking reach). However, athletic success depends heavily on many other physical and technical factors.
Some famous athletes do have notable ape indices — Michael Phelps, for example, has an arm span significantly greater than his height, which contributed to his swimming dominance. However, many elite athletes across all sports have completely average ape indices, confirming that it is just one of many physical attributes that contribute to performance.