BMI Calculator
Enter your height and weight to get your BMI, the WHO category it falls into, and the weight range that would place you in the normal band at your height.
BMI is a rough screening measure for adults. It ignores muscle mass, age and body composition, and is not a medical diagnosis.
About this tool
BMI is weight divided by height squared. It was designed to describe populations, not individuals, which is why it is a screening indicator rather than a diagnosis: it cannot tell muscle from fat, and it reads high for athletes and low for people who have lost muscle.
The WHO adult bands are under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight and 30 or above obese. Different cut-offs apply for children, for older adults and for some Asian populations, where the overweight threshold is often set nearer 23.
Frequently asked questions
- What is the BMI formula?
- Metric: weight in kilograms divided by height in metres squared. Imperial: 703 × weight in pounds divided by height in inches squared.
- What is a healthy BMI?
- For most adults, 18.5 to 24.9. Below that is classed as underweight, 25 and above as overweight.
- Is BMI accurate for athletes?
- No. Muscle is denser than fat, so a muscular person can score as overweight while carrying very little body fat. Waist measurement or body-fat percentage tells you more.
- Does BMI work for children?
- Not with these bands. Children are assessed against age- and sex-specific percentile charts instead of fixed cut-offs.