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What is the Ape Index?
The ape index, also called the ape factor or gorilla index, is a measurement comparing your arm span (fingertip to fingertip) to your height. It can be expressed as a ratio (arm span divided by height) or as a simple difference (arm span minus height). A positive ape index means your arm span exceeds your height, which is generally advantageous in sports requiring reach, such as climbing, swimming, boxing, and basketball.
The average person has an ape index very close to 1.0, meaning their arm span approximately equals their height. However, there is significant natural variation. Some elite climbers and swimmers have ape indices well above 1.0, giving them a mechanical advantage in their sport. The measurement has become a standard metric in climbing communities and combat sports.
How to Calculate
Both expressions are commonly used. Climbers tend to prefer the difference method (e.g., "+2 inches"), while scientific literature often uses the ratio. To measure your arm span, stand against a wall with arms fully extended horizontally, and measure from the tip of one middle finger to the other.
Importance in Sports
| Sport | Ideal Ape Index | Advantage |
|---|---|---|
| Rock Climbing | > 1.00 | Greater reach between holds |
| Swimming | > 1.03 | Longer stroke length, more pull area |
| Boxing/MMA | > 1.02 | Reach advantage in striking |
| Basketball | > 1.05 | Shot blocking, rebounding reach |
Famous Athletes with Notable Ape Indices
- Michael Phelps: 6'4" height, 6'7" wingspan, ape index of +3 inches (1.04 ratio)
- Jon Jones (UFC): 6'4" height, 84.5" wingspan, ape index of +8.5 inches (1.11 ratio)
- Manute Bol: 7'7" height, 8'6" wingspan, ape index of +11 inches (1.10 ratio)
- Adam Ondra (climber): Known for a significantly positive ape index aiding his climbing
Frequently Asked Questions
What is a good ape index for climbing?
Any positive ape index (ratio above 1.0) is considered beneficial for climbing. An ape index of +2 to +4 inches is common among elite climbers. However, many world-class climbers have neutral or even slightly negative ape indices, showing that technique, strength, and flexibility matter far more than reach alone.
Can I change my ape index?
No. Your ape index is determined by your skeletal structure and cannot be changed through training. However, you can maximize your effective reach through shoulder mobility exercises and proper body positioning technique in your sport.
How do I measure my arm span accurately?
Stand flat against a wall with your arms extended fully to the sides at shoulder height. Have someone mark the tip of each middle finger on the wall, then measure the distance between the marks. Make sure your shoulders are against the wall and arms are level for an accurate measurement.