Toolstia / BMI calculator
BMI calculator
Enter your weight and height to get your body mass index (BMI), the WHO category it falls in, and the weight range that corresponds to a BMI of 18.5 to 24.9 at your height.
BMI is a rough screening number for adults. It does not measure body fat, and it is not suitable for children, pregnancy or athletes with high muscle mass. It is not medical advice.
How it works
- Choose metric or imperial.
- Enter your weight and height.
- Read your BMI, your category and your healthy range.
The formula
BMI is your weight in kilograms divided by your height in metres squared. A person weighing 70 kg at 1.75 m has a BMI of 70 / (1.75 x 1.75) = 22.9.
WHO adult categories
Under 18.5 is underweight, 18.5 to 24.9 is the healthy range, 25 to 29.9 is overweight, and 30 or more is obese. This tool uses these standard cut-offs.
Asian populations
Health bodies in several Asian countries advise lower cut-offs, because health risks can rise at lower BMI levels. A BMI of 23 or above is often treated as increased risk and 27.5 or above as high risk. Ask your doctor which scale applies to you.
What BMI cannot tell you
BMI does not measure body fat or where it is carried, and it does not separate muscle from fat. It is not designed for children, teenagers, pregnant women or very muscular people. Use it as a rough starting point, not a diagnosis.
Questions
Is this medical advice?
No. It is a general screening number. A doctor can interpret it for your age, build and health.
Is my data stored?
No. The numbers are calculated in your browser and are gone when you close the page.
What is a healthy BMI?
The WHO healthy range for adults is 18.5 to 24.9.
Does it work for children?
No. Children and teenagers are assessed with age and sex specific charts, not these adult cut-offs.