What is the Ape Index?
The ape index (also called the ape ratio) describes the relationship between a person's wingspan (arm span) and their height. It takes its name from the fact that apes typically have wingspans that greatly exceed their height — a trait that gives them an advantage when climbing and swinging.
Have you ever heard about the Vitruvian Man? It is Leonardo da Vinci's famous drawing of a man inscribed in a square and circle. Da Vinci's idea was to present a perfect human being where every measurement is symmetrical. In this ideal, a person's wingspan equals their height exactly — giving an ape index of 1.0. In reality, most people are close to 1.0, but athletes in certain sports may have significantly higher values.
How to Measure Your Ape Index
The formula is simple:
APE INDEX = Wingspan ÷ Height
Where Wingspan is the distance from fingertip to fingertip with both arms extended horizontally, and Height is your standing height.
How to Measure Your Height
- Stand straight against a wall with your back flat against it — do not slouch.
- Mark the wall at the top of your head.
- Measure from the floor to the mark.
How to Measure Your Wingspan
- Stand up straight with both arms extended parallel to the floor.
- Have someone measure the distance from fingertip to fingertip.
- If measuring alone, use a long tape measure against a wall.
Wingspan to Height Ratio: Result Interpretation
| Ape Index | Category | What It Means |
|---|---|---|
| < 0.97 | Negative | Height exceeds wingspan. Less reach advantage in sports. |
| 0.97 – 1.02 | Neutral | Wingspan ≈ height. Close to the Vitruvian Man ideal. |
| 1.02 – 1.06 | Slightly Positive | Small wingspan advantage. Helpful in reach-based sports. |
| 1.06 – 1.12 | Positive | Notable advantage in swimming, boxing, basketball, climbing. |
| > 1.12 | Elite | Exceptional wingspan advantage found in elite athletes. |
There is also an alternative ape index formula that calculates the difference (Wingspan − Height) rather than the ratio. With this method, the result is expressed in centimeters or inches rather than as a ratio, so don't be surprised if you see an ape index of "+5 cm" or "+2 in" — both formulas describe the same relationship, just in different ways.
Sports Where the Ape Index Matters
- Swimming — A longer wingspan increases stroke length, directly translating to more speed per stroke. Michael Phelps (ape index ≈ 1.07) is the most cited example.
- Basketball — A longer reach helps with rebounding, blocking shots, and stealing passes.
- Boxing & Martial Arts — Greater reach means you can land punches while staying farther from your opponent's fists.
- Rock Climbing — A positive ape index allows climbers to reach holds that are farther apart.
- American Football (Receivers) — A wide catch radius is a notable advantage for wide receivers.
- Volleyball — Longer arms improve blocking and spiking at the net.
- Rowing — A longer reach at the catch position can add efficiency to each stroke.
Notable Athletes and Their Ape Index
| Athlete | Sport | Height | Wingspan | Ape Index |
|---|---|---|---|---|
| Michael Phelps | Swimming | 193 cm (6'4") | 201 cm (6'7") | ≈ 1.04 |
| LeBron James | Basketball | 206 cm (6'9") | 213 cm (7'0") | ≈ 1.03 |
| Viktor Bout (boxing) | Boxing | 188 cm (6'2") | 198 cm (6'6") | ≈ 1.05 |
| Adam Ondra | Rock Climbing | 186 cm (6'1") | 192 cm (6'4") | ≈ 1.03 |
Tips for Accurate Measurement
- Measure barefoot for height; shoes add height unevenly.
- Measure wingspan in the morning — you are slightly taller then due to spinal decompression.
- Keep arms perfectly horizontal and fully extended — drooping arms give a shorter measurement.
- Have someone assist you for the most accurate wingspan measurement.