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Ponderal index calculator

The ponderal index (Rohrer index) relates your weight to the cube of your height, making it a sharper gauge of leanness than BMI for very tall or short people. Enter your numbers for an instant result and category.

Ponderal index

Weight and height. Results update live.

Ponderal index
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Enter your weight and height.

Category
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BMI for reference
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Formula: PI = weight (kg) / height (m)3. Normal adult range: 11 to 14.
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Why the cube of height

The ponderal index divides weight in kilograms by height in meters cubed, so it scales more naturally with body volume than BMI, which uses height squared. That makes it fairer when comparing leanness across very different heights, for example a 150 cm adult versus a 195 cm athlete, where BMI can mislead.

Reading your result

Adults typically land between 11 and 14. Below 11 suggests underweight, 11 to 14 is the normal band, 14 to 15 leans overweight, and above 15 points toward obesity. Like BMI it cannot tell muscle from fat, so pair it with a body fat estimate for the full picture.

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Ponderal Index FAQs

What is the ponderal index formula?
Divide weight in kilograms by height in meters cubed: PI = kg / m^3. A 70 kg person at 1.75 m has a PI of 70 / (1.75^3), about 13.1, which sits in the normal band.
What is a normal ponderal index?
For adults, 11 to 14 is generally considered normal. Under 11 is underweight, 14 to 15 is overweight, and above 15 is usually classified as obese.
Is the ponderal index better than BMI?
It scales better with height, so it is fairer for very tall or very short people. For average heights the two usually agree, and neither can distinguish muscle from fat.
What units does this calculator use?
Kilograms and centimeters. The math converts your height to meters internally, then cubes it, so just enter the numbers you see on your scale and tape measure.
Does the ponderal index work for children?
Pediatricians sometimes use it for newborns, but the 11 to 14 adult bands do not apply to children. Use age and sex specific growth charts for kids instead.
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