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Ponderal Index Calculator

A height-adjusted alternative to BMI.

Result

13.06

How it is calculated

The ponderal index divides body mass by the cube of height: PI = weight ÷ height³. Enter weight in kilograms and height in centimetres; the tool converts height to metres (height ÷ 100), cubes it and divides, so the unit is kg/m³. Both values must be above zero, otherwise there is no result. The answer is rounded to two decimals. Because it uses the cube, it relates to the same mass-for-height idea as BMI (which squares height) but is sensitive to height in a different way. The tool gives the number only; reference ranges depend on age and context, so use the value as a comparison between measurements, not as a diagnosis.

Worked example

Take weight 70 kg and height 175 cm. Step 1: height in metres = 175 ÷ 100 = 1.75. Step 2: cube it: 1.75 × 1.75 × 1.75 = 5.359375. Step 3: divide the weight: 70 ÷ 5.359375 ≈ 13.06. The tool shows 13.06 kg/m³.

Try this example →

Common mistakes

  • Entering height in metres. The field expects centimetres; typing 1.75 would be read as 1.75 cm and give an absurdly large value.
  • Entering weight in pounds. The formula assumes kilograms.
  • Mixing it up with BMI. BMI divides by height squared, so the two numbers are on different scales and cannot be compared.
  • Treating one value as a verdict. A single index does not describe body composition, and healthy ranges depend on age.
  • Rounding the height before cubing. A small rounding error in height is magnified by the cube.

About this calculator

The ponderal index measures leanness using mass ÷ height³ (typically expressed as kg/m³), rather than BMI's mass ÷ height², making it less distorted for people who are unusually tall or short since it scales weight against volume rather than area.

It's used clinically to assess whether newborns are proportionally sized for their length (a common flag for growth issues), and in sports science as an alternative to BMI for very tall athletes — basketball players, for instance — whose BMI reads artificially high purely because of their height.

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