Ponderal index calculator
The ponderal index relates weight to height cubed instead of squared, so it changes less with height than BMI does. Enter your weight and height to get it in kilograms per cubic metre.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose metric (kilograms and centimetres) or US units (pounds, feet and inches).
- Enter your weight and height.
- Read the ponderal index in kg/m³ and the BMI beside it.
How it works
Ponderal index = weight (kg) ÷ height (m)³
For US units the calculator converts first, using the exact values 1 lb = 0.45359237 kg and 1 in = 0.0254 m. BMI is weight ÷ height², so the ponderal index equals BMI divided by height in metres.
Worked example
A person who weighs 70 kg and is 175 cm tall: 1.75³ = 5.359375, and 70 ÷ 5.359375 = 13.06 kg/m³. The same person has a BMI of 70 ÷ 3.0625 = 22.9.
Good to know
Like BMI, the ponderal index says nothing about muscle, fat distribution or health. It is an estimate for information only, not medical advice.
Frequently asked questions
What is the ponderal index?
It is weight in kilograms divided by height in metres cubed, also called Rohrer's index. It is a screening number that describes how heavy a body is for its height; it is not a diagnosis.
How is it different from BMI?
BMI divides weight by height squared, the ponderal index by height cubed. Because body mass grows roughly with the cube of height, some researchers prefer the cubed form for very tall or very short people, and for newborns.
What is a normal ponderal index?
There is no single official range for adults, and sources differ, so this calculator does not label your result. BMI has widely used adult categories, which is why it is shown beside the ponderal index. Ask a doctor how to read either number for you.
Can I use it for children?
The formula works for any weight and height, but interpreting it for children and babies needs age-specific reference charts, which this tool does not include.