The ideal ape index or arm-to-height ratio is 1:1 [8]. People can calculate this ratio by dividing the wingspan (the distance between the fingertips of both hands with the arms outstretched) by height.
For example, if a person has a wingspan of 180 cm and their height is also 180 cm, the ape index will be 180/180 or 1:1.
However, even if the wingspan and height have a difference of 2-3 cm, it’s practically indistinguishable from 1:1. In fact, people aren’t considered disproportionate up to a difference of about 10 cm.