BMI Calculator

Choose Metric or Imperial and enter weight and height in the fields shown. In Metric mode, a height of 1.75 m is entered as 1 meter and 75 centimeters. In Imperial mode, use the separate feet and inches fields. Use a recent measurement and check that the selected unit system matches your entries.

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FORMULA AND EXAMPLE

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BMI = weight in kilograms ÷ height in meters squared. At 70 kg and 1.75 m, the calculation is 70 ÷ (1.75 × 1.75), giving about 22.9 kg/m². Squaring the height is essential; dividing by height only once gives a different quantity.

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WHAT THE NUMBER REPRESENTS

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BMI compares weight with height. It does not directly measure body-fat percentage or distinguish fat from muscle and bone. Two people can have the same BMI and different body composition. A category attached to the result is a screening reference, not a diagnosis or a complete assessment of health.

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INTERPRETATION DEPENDS ON CONTEXT

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CDC adult BMI categories apply to adults aged 20 and older. Children and teenagers need age- and sex-specific interpretation rather than the adult categories. Pregnancy and individual clinical circumstances can also make a simple weight-to-height interpretation inappropriate.

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If a result looks unexpected, check the height fields, units, and decimal entry before interpreting it. Small changes in a measured height can affect the result because height is squared. Use a qualified health professional for an individual assessment rather than choosing a weight target from this number alone.

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Reference: Centers for Disease Control and Prevention, “About BMI.”