About the Ape Index Calculator
The ape index compares your arm span — fingertip to fingertip with arms stretched out sideways — to your standing height. Climbers usually quote it as a difference ("plus 5 centimetres" or "+2 inches"), while coaches and scouts in boxing, basketball and swimming often use the wingspan-to-height ratio. This calculator gives you both, in centimetres or inches.
A positive ape index means your wingspan is longer than you are tall, which extends reach on the wall, in the ring and on defence. A negative value means shorter arms relative to height. Most adults land within a few centimetres of zero, which is why the classic rule of thumb says arm span roughly equals height.
Measure barefoot against a wall for height, and for wingspan stand with your back to a wall, arms level at shoulder height, and measure between the tips of your middle fingers. Small measuring errors matter here because the result is a small difference between two large numbers.
With the default inputs, the ape index (wingspan − height) is 5. Change any value above to recalculate instantly.
How to use the ape index calculator
- 1Choose centimetres or inches.
- 2Measure your barefoot height against a wall and enter it.
- 3Stand with arms straight out at shoulder height and measure fingertip to fingertip.
- 4Read your ape index, ratio and classification.
Formula and method
The ape index is the simple difference between arm span and standing height, kept in the units you measured in (centimetres or inches). The ratio divides wingspan by height, so 1.00 means they are identical, 1.03 means a wingspan 3% longer than height and 0.98 means 2% shorter.
The classification bands used here (neutral within ±1%, positive above 1%, strongly positive above 5%) are a convenient convention rather than a formal standard. Because both measurements are large and the difference is small, a 1 cm error in either one moves the result noticeably — measure carefully.
- Wingspan
- Arm span, middle fingertip to middle fingertip
- Height
- Barefoot standing height
Worked examples
175 cm tall with a 180 cm wingspan
180 − 175 = +5 cm ape index. 180 ÷ 175 = 1.029, so the wingspan is about 2.9% longer than height — a mild reach advantage.
5′10″ (70 in) with a 73-inch wingspan
73 − 70 = +3 inches, which is 7.6 cm. The ratio 73 ÷ 70 = 1.043, a clearly positive ape index of the kind climbers value.
165 cm tall with a 162 cm wingspan
162 − 165 = −3 cm. The ratio is 0.982, about 1.8% shorter arms than height, which counts as a negative ape index.
Frequently asked questions
What is a good ape index for climbing?+
Any positive ape index helps with reach between holds, and many strong climbers are a few centimetres positive. But technique, finger strength and body weight matter far more — plenty of elite climbers have a neutral or negative ape index.
Is wingspan usually equal to height?+
Roughly, yes. For most adults arm span is within a few centimetres of height, which is the basis of the old Vitruvian rule. Arm span is even used clinically to estimate height when someone cannot stand.
How do I measure my wingspan accurately?+
Stand with your back flat against a wall, raise both arms straight out at shoulder height with palms facing forward, and have someone mark the tips of your middle fingers. Measure between the marks and repeat twice.
Can you increase your ape index?+
No. Wingspan is set by bone length, so once you have stopped growing it does not change with training. Improving shoulder mobility can increase your effective reach slightly, but not your measured arm span.
Why does the ape index matter in boxing and swimming?+
Longer arms give boxers more reach to land punches from outside an opponent’s range, and give swimmers a longer pull through the water on each stroke. In basketball, wingspan affects shot blocking and rebounding.