What is the ape index?
The ape index (also called the ape factor or reach) compares your arm span — measured fingertip to fingertip with arms stretched horizontally — to your standing height. A positive ape index means your wingspan is longer than your height, which is common among elite climbers, swimmers, and boxers because it gives extra reach.
How this calculator works
The calculator subtracts your height from your wingspan: Ape Index = Wingspan − Height. A result of 0 means your wingspan equals your height (the historical average for most people); a positive number means an above-average reach, and a negative number means a below-average reach relative to height. The wingspan-to-height ratio expresses the same comparison as a percentage.
Ape index is a fun, informal measurement rather than a precise athletic predictor — reach, limb proportions, and technique all matter differently depending on the sport.