The imperial form uses pounds and feet + inches, the units most
Americans use day-to-day. The calculator converts your inputs to
kilograms and centimetres internally and uses the standard
BMI = weight (kg) / height (m)² formula. The lb/ft+in
form has separate input boxes for feet and inches because most
scales report weight in lb but height is naturally given as ft+in.
How the calculation works
For a 165 lb person who is 5 ft 9 in (69 in / 175.26 cm) tall, BMI = 75 ÷ (1.7526 × 1.7526) = 24.4. The lb/ft+in form and the kg/cm form produce the same number, just with different unit inputs.
What you get beyond BMI
Beyond the BMI value, the calculator shows your WHO category (underweight, normal, overweight, obese) with a colour-coded gauge, plus BMI Prime, Ponderal Index, body-fat percentage, healthy weight range (in lb), ideal weight (Devine, in lb), lean body mass (Boer, in lb), BMR and TDEE at five activity levels.
Next steps
- lb + inches form (this page in different wording)
- Metric BMI calculator (kg + cm)
- Asian BMI calculator