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BMI Calculator

Calculate your Body Mass Index instantly with metric or imperial units. See your weight category and healthy range.

Your measurements

Results update live as you type.

Your BMI
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Enter your measurements.

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How BMI is calculated

BMI is your weight in kilograms divided by the square of your height in meters. Imperial inputs are converted first, so both unit systems produce the same number. The result updates live as you type, alongside your WHO weight category and the healthy weight range for your height.

What BMI does not tell you

BMI is a screening shortcut, not a diagnosis. It cannot distinguish muscle from fat, so athletes can score as overweight while being very fit, and it does not account for age, sex or body composition. Treat it as one data point among many.

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BMI Calculator FAQs

What is a healthy BMI?
The WHO defines 18.5 to 24.9 as the healthy range for adults. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is obesity.
Is BMI accurate for athletes?
Not always. Muscle is denser than fat, so muscular people can land in the overweight range with low body fat. Pair BMI with waist measurement or body-fat estimates for a fuller picture.
Does BMI work for children?
Children's BMI is interpreted with age-and-sex percentile charts, not adult cutoffs. This calculator uses adult categories, so it is meant for ages 18 and up.
How often should I check my BMI?
Monthly is plenty. Weight fluctuates daily with water and meals, so a monthly trend tells you far more than any single reading.
Is my data stored anywhere?
No. Your height and weight are used for the live calculation only and never leave your browser.
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