Adult BMI Calculator: Metric and Imperial
Calculate adult BMI from kilograms and centimeters or pounds and inches. See the screening category and understand what BMI can and cannot tell you.
Your inputs
Choose the units and assumptions that match your data. Example inputs are illustrative.
Your result
Enter your values, then choose Calculate.
Results are calculated in your browser. Display rounding does not change the underlying calculation.
Calculation breakdown
Method, assumptions and worked example
How it works
BMI = weight in kilograms ÷ height in meters squared. Pounds are converted using 0.45359237 kg per pound and inches using 2.54 cm per inch. Categories use the unrounded result: below 18.5, 18.5 to below 25, 25 to below 30, and 30 or above.
Worked example
At 70 kg and 175 cm, BMI is 70 ÷ 1.75² = 22.86, in the CDC healthy-weight screening category.
Using the result
BMI is a screening measure, not a diagnosis or a measure of fat percentage. Muscle mass, age, ethnicity and other health information affect interpretation. This tool uses adult categories for ages 20 and over; child and teen BMI needs age- and sex-specific percentiles. Pregnancy requires different assessment.
Frequently asked questions
Does BMI measure body fat?
No. It combines height and weight and cannot distinguish fat from muscle.
Should I round before choosing the category?
No. Categories here use the full calculation; the displayed value is rounded.
Method review and references
Formula and content reviewed on 10 October 2026. Worked examples are hypothetical. Methods and assumptions are explained on each page. Health estimates are not clinical measurements; symbolic tools are for entertainment.