Question 1

What is the Ponderal Index?

Accepted Answer

Ponderal Index (PI), also called Rohrer Index, is weight divided by height cubed. Unlike BMI which divides by height squared, PI scales mass with the cube — the geometrically correct relationship for three-dimensional objects. This produces less distortion at height extremes.

Question 2

Is Ponderal Index better than BMI?

Accepted Answer

For very tall or very short individuals, PI is theoretically better than BMI because it scales correctly with mass-volume relationships. In practice, both are screening tools with similar predictive value for population-level adiposity. BMI is far more widely cited.

Question 3

Is my data private?

Accepted Answer

Yes. All math runs in your browser. We never see, store, or transmit your inputs.

PI	Category
< 11	Underweight
11–14	Healthy range
≥ 14	Above typical range

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