How to calculate Body Mass Index

1. Enter weight with its unit

   Pick "Weight unit" (kg, g, lb, oz, st, t — stone is a decimal, e.g. 11.5 = 11 st 7 lb) and type the number into "Weight". Anything 0–1,000,000 is accepted by the schema.

2. Enter height with its unit

   Pick "Height unit" (cm, m, mm, in, ft, yd — feet is decimal, e.g. 5.75 ≈ 5 ft 9 in) and type the number into "Height". Mix the systems freely: lb + cm is fine.

3. Press Run

   Result returns bmi (rounded to 2 decimals), category (Underweight / Normal range / Overweight / Obese I-III) with a categoryId, healthyWeightMinKg / MaxKg for the WHO 18.5–25 band, ponderalIndex and bmiPrime.

4. Read responsibly

   Output also includes weightKg, heightM, and the exact units you used. BMI is a screening number, not a diagnosis — athletes, pregnant people, and elderly populations need different reference ranges.