What the ape index is
The ape index compares your arm span, measured fingertip to fingertip with arms stretched out sideways, with your height:
- Ape index = arm span − height, in inches or centimeters
- Span ratio = arm span ÷ height
For most people span and height are nearly equal, giving an ape index close to zero and a ratio near 1.0. A positive ape index means longer arms relative to height.
Example
A climber 69 inches tall (5 ft 9 in) with a 71-inch span has an ape index of +2 inches and a ratio of 1.03.
How to measure
- Stand with your back against a wall, arms stretched out at shoulder height.
- Have someone mark the tips of your middle fingers.
- Measure between the marks, and measure your height without shoes.
Why it matters in sport
- Climbing: a longer reach helps on long moves between distant holds and in bouldering. Free soloist Alex Honnold is often quoted with a span about 3 inches longer than his height.
- Swimming: long arms pull more water per stroke. Michael Phelps reportedly has a span of about 6 ft 7 in for a height of 6 ft 4 in.
- Combat sports: boxers and MMA fighters list “reach,” essentially arm span, alongside height and weight.
- Basketball and volleyball: wingspan affects blocking, rebounding and defense; NBA draft measurements report it.
Keep it in perspective
The ape index is one physical trait among many. In climbing, technique, footwork, finger strength, flexibility and route reading matter much more. Shorter climbers often excel on routes with small, close holds, and many routes can be climbed with different sequences adapted to reach. Use the ape index to understand your style, not to limit your ambitions.
Typical ranges
| Span ratio | Description |
|---|---|
| Below 0.98 | Shorter span than height |
| 0.98 to 1.03 | Neutral, the most common |
| 1.03 and above | Long reach |