← Measurement Conversions

Illustration of a person beside a height scale, with a tape measure around the waist and modern scales on the floor.

Body Indexes

Enter weight, height and waist size

Enter weight, height, and waist size in any units; each column stays in sync. BMI uses weight and height; BRI uses waist size and height.

Weight

Whole stones and pounds (LB) —

Height

Whole feet and inches —

Waist Size (BRI only)

Body Mass Index (BMI) - Traditional —
Body Mass Index (BMI) - Alternative —
Body Roundness Index (BRI) —

Traditional BMI = kg ÷ m². Alternative BMI = 1.3 × kg ÷ m^2.5 (Nick Trefethen, University of Oxford). BRI = 364.2 − 365.5 × √(1 − (waist ÷ 2π)² ÷ (height ÷ 2)²) with waist and height in metres.

Related converters: Weight, Height, and Nutritional Energy.

Note: We do not check the numerical validity of your inputs to ensure sensible values for a human so have fun :). Nothing here constitutes health advice of any kind.