Ape Index Calculator
Compare arm span with standing height using a ratio and absolute difference.
How the result changes
Only arm span changes; all other inputs stay at your current values. The line illustrates the formula across the shown range. This is not a forecast of real-world outcomes.
About this calculation
Ape Index Calculator: Compare arm span with standing height using a ratio and absolute difference. Enter arm span, standing height; the reported quantities are ape index ratio, arm span minus height (cm). The equations and examples below show how those inputs lead to the result and where the model's assumptions matter.
Formula
ape index ratio = arm span / height
Worked example
With Arm span: 182 cm, Standing height: 178 cm, ape index ratio is 1.022472.
Method and inputs
Measure fingertip-to-fingertip arm span with arms extended horizontally and compare it with standing height. The ratio divides span by height; the difference subtracts height from span. Both lengths must be recorded in centimeters here.
Worked example
With a span of 182 centimeters and height of 178 centimeters, the ratio is about 1.0225 and the difference is 4 centimeters. The person’s span is slightly longer than their height.
The ratio and difference answer related but distinct questions. A 4-centimeter span advantage is proportionally larger for a 140-centimeter person than for a 200-centimeter person. The ratio accounts for that size difference, while the signed centimeters remain easy to visualize.
How to read the result
A ratio above one means arm span exceeds height; below one means the opposite. The difference gives an intuitive length, while the dimensionless ratio helps compare people of different sizes. Neither value is a measure of athletic skill.
A climbing-reach discussion may care about standing reach or shoulder flexibility more than fingertip span. Two people with the same ape index can have different limb segment proportions. Avoid treating this one anthropometric comparison as a direct performance forecast.
Assumptions and checks
Measurements should be taken without shoes and with consistent posture. Shoulder mobility, wingspan measurement technique and normal variation can affect the result. This calculator makes no prediction about performance or health.
Do not divide height by span if you intend this convention, because the reciprocal reverses comparisons. A few centimeters of tape placement can matter when the ratio is near one. Record repeated measurements if precision matters.
Common questions
What does the ape index calculator calculate?
It compares arm span with height as both a ratio and a signed centimeter difference. Values above one and positive differences indicate a longer span.
When should I recalculate or check another method?
Recalculate after obtaining more reliable measurements or when comparing results from sources that use the difference rather than ratio convention. State which convention was used when sharing an ape index.
Inputs
- Arm span (cm)
- Standing height (cm)