Body mass index, or BMI, compares your weight with your height. Enter your height and weight in kilograms and centimetres, or in pounds, feet and inches, and this free BMI calculator shows your BMI, the adult category and a healthy weight range for your height.
| Category (adults) | – |
| Healthy weight range for your height | – |
How it works
BMI = weight in kilograms ÷ (height in metres)². For pounds and inches the same result comes from 703 × pounds ÷ inches². For adults, the World Health Organization groups BMI as under 18.5 underweight, 18.5 to 24.9 healthy weight, 25 to 29.9 overweight and 30 or more obese.
BMI is a simple screening number. It does not measure body fat or muscle, and it can be misleading for athletes, older adults and some ethnic groups. It is not meant for children, teenagers or pregnant women.
Example
A person 170 cm tall who weighs 70 kg has a BMI of 70 ÷ (1.70 × 1.70) = 24.2, which is in the healthy weight range.
Frequently asked questions
Is BMI accurate?
It is a quick guide for adults, but it does not show how much of your weight is fat, muscle or bone. A doctor can give a fuller picture.
What is a healthy BMI?
For most adults, 18.5 to 24.9.
Can I use this for children?
No. Children and teenagers use age and sex-specific charts. Ask a doctor.
More free tools: Calorie calculator · Unit converter · All free tools
This calculator is for general information only and is not medical advice. Talk to a doctor or registered dietitian about your health.