What does it mean? First of all, the ape index is often an indicator for your sports ability. Those with longer arms tend to have an advantage in certain sports, such as rock climbing, basketball, swimming, tennis, golf, pitching a baseball, or any other throwing or swinging motion. The ape index is usually defined as the ratio of arm span to height. However, an alternative approach is arm span minus height with the result being positive, 0 or negative. Unlike the unitless ratio, this calculation produces a numeric value in the units of measurement used to represent the height and arm span. Your ape index – also referred to as your ape factor – is a measurement of your wingspan in ratio to your height. Most humans have a neutral ape index, or a ratio of 1, which means that the length from your fingertip to fingertip is the same as your height.