How to use the BMI Calculator tool
3 simple steps · under a minute
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Choose your units
Use metric (kg and cm) or imperial (pounds, feet and inches).
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Enter height and weight
Type your height and current weight.
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Read your BMI
See your BMI, its category and the healthy weight range for your height.
About BMI calculator
Body Mass Index (BMI) is a quick way to check whether your weight is in a healthy range for your height. It is calculated by dividing your weight in kilograms by the square of your height in metres, and is used by doctors and the World Health Organization as a first screening measure.
BMI is a useful guide for most adults, but it does not measure body fat directly. Very muscular people can have a high BMI without excess fat, and BMI may be less accurate for older adults, pregnant women and some ethnic groups. For children and teenagers, BMI is judged against age- and sex-specific charts instead.
Metric and imperial
Works in kilograms and centimetres, or pounds, feet and inches.
Healthy weight range
Shows the weight range that gives a healthy BMI for your height.
Clear BMI scale
A colour scale shows where you sit between underweight and obesity.
Frequently asked questions
How is BMI calculated?
BMI = weight (kg) ÷ height (m)². In imperial units, BMI = 703 × weight (lb) ÷ height (in)².
What is a healthy BMI?
For adults, a BMI from 18.5 to 24.9 is considered a healthy weight. Below 18.5 is underweight, 25 to 29.9 is overweight and 30 or above is obesity.
Is BMI accurate?
It is a good general guide for most adults, but it cannot tell muscle from fat. Waist size and other measures give a fuller picture.
Is BMI different for Asian adults?
Some health bodies, including in India, use lower cut-offs for Asian adults: 23 or above as overweight and 25 or above as obese, because health risks rise at lower BMIs.
Is this medical advice?
No. BMI is a screening tool. Talk to a doctor about your weight and health.