Free BMI Calculator

Enter your weight and height to see your body mass index and the range it falls in — metric or imperial.

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BMI · Normal

BMI is a general screening figure for adults and doesn't account for muscle, build, age, or sex. It isn't medical advice.

How to use / FAQ

Choose metric or imperial units, enter your weight and height, and your BMI is calculated instantly along with the range it falls in. Nothing is stored or sent anywhere.

How is BMI calculated?

BMI is your weight in kilograms divided by the square of your height in metres. Imperial values are converted to metric first, so both unit systems give the same result.

What do the ranges mean?

The tool uses the standard adult ranges: below 18.5 is underweight, 18.5–24.9 is the normal range, 25–29.9 is overweight, and 30 or above is in the obesity range.

Does BMI work for children or athletes?

Not well. The adult ranges here don't apply to under-18s, who use age- and sex-specific percentiles, and very muscular people can read as 'overweight' despite low body fat. Treat it as a rough adult screening figure only.

Is BMI an accurate measure of health?

BMI is a quick general screening number, not a diagnosis. It doesn't distinguish muscle from fat or account for age, sex, or body build, so treat it as a rough guide rather than medical advice. For daily energy needs rather than a size screening, try the calorie & TDEE calculator.