The APE Index (Arm span to Height Equivalent) is a measurement of a person’s arm span (wingspan) compared to their height. It is calculated by subtracting your height from your arm span. A positive APE index means your arms are longer than your height, which is often considered advantageous in sports like rock climbing, surfing, and martial arts.

Stand with your back against a wall and extend your arms out to the sides parallel to the floor (like a ‘T’). Have a friend measure the distance from the tip of your left middle finger to the tip of your right middle finger. Ensure your arms are fully extended and level for the most accurate wingspan measurement.

Stand barefoot against a flat wall with your heels, buttocks, shoulders, and head touching the wall. Look straight ahead. Have someone place a flat object (like a book) on your head, parallel to the floor, and mark the wall. Measure from the floor to the mark. Do not measure your height with shoes on, as this will skew your APE Index results.

In rock climbing, a positive APE index (longer arms than height) allows you to reach further between holds, rest more easily on smaller ledges, and bridge gaps that shorter-armed climbers might struggle with. However, technique, finger strength, and footwork are ultimately more important than a high APE index.

The APE Index is typically the difference between your arm span and height (e.g., +2 inches or +5 cm). The wingspan ratio (or height-to-arm span ratio) is your arm span divided by your height (e.g., 1.03). Both measure the same physical proportion but express it differently. This calculator provides both values for your convenience.

Yes, a longer wingspan can provide a greater reach for paddling, helping you catch waves earlier and maintain speed. It also helps with balance and popping up on the board. Many professional surfers have a positive APE index, though board feel and wave reading skills are equally critical.