BMI Calculator
Enter your height and weight to calculate adult BMI, compare reference ranges, and see what the number does and does not tell you.
What BMI measures
BMI is weight in kilograms divided by height in metres squared. It is a practical screening measure for weight status, not a direct measurement of body fat.
For adults, common reference categories place 18.5–24.9 in the healthy-weight range, 25.0–29.9 in the overweight range, and 30 or above in the obesity range.
Why the number needs context
BMI can be less representative in people with high muscle mass. Abdominal fat also matters, so waist measurement can add useful context.
Some guidelines use lower BMI thresholds for certain populations because cardiometabolic risk can occur at lower BMI.
What to check next
For adults with BMI below 35, waist-to-height ratio can be used alongside BMI as a practical estimate of central adiposity. A simple reference is a waist below half of height.
Blood pressure, blood glucose, blood lipids, physical activity and weight trend can also put the number in context.
Important limitations
Children and teenagers need age- and sex-specific growth references. Pregnancy has separate weight-gain guidance. Older adults and people with high muscle mass may need additional context when BMI is interpreted.
Sources
About this tool
Free BMI calculator for adults. Enter height and weight to see BMI, reference categories, a height-based weight range and optional waist-to-height context.
Many browser-based tools process input on your device; external-service tools may send network requests.
How to use
Use the fields above
Enter your height and weight to calculate adult BMI, compare reference ranges, and see what the number does and does not tell you.
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