BMI calculator
ReadyCalculate your body mass index from height and weight in metric or imperial units and see your WHO weight category and the weight range for a BMI of 18.5–24.9.
This result is an estimate from a general formula and is not a medical diagnosis or treatment advice. Talk to a healthcare professional about your health.
How to use
- Choose metric (cm, kg) or imperial (feet, inches, pounds).
- Enter your height and weight – your BMI, its category and a healthy weight range for your height appear straight away.
Formula
- BMI = weight (kg) ÷ height (m)²
- Imperial: BMI = 703 × weight (lb) ÷ height (in)²
- WHO: under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30 and over obesity (class I–III)
Worked example
170 cm and 65 kg → BMI 22.5 (healthy weight) 5 ft 9 in and 160 lb → BMI 23.6 (healthy weight)
FAQ
Is BMI accurate for everyone?
No. BMI is a screening measure based only on height and weight. It doesn’t distinguish muscle from fat, so it can mislead for athletes, older adults, pregnant people and children. Talk to a healthcare professional about your health.
Can I use this for children?
No. Children and teenagers need age- and sex-specific BMI percentiles. This calculator uses adult cut-offs.
Do different countries use different cut-offs?
Yes. This page uses the WHO adult categories. Some health bodies use lower cut-offs for people of Asian descent – for example Japan treats a BMI of 25 or more as obesity.