Reference formulas and worked examples below keep their stated units. Monetary examples use USD; dimensional examples use US customary units unless labeled otherwise. Metric calculator inputs are converted to these reference units before calculation. Choosing another currency does not convert example amounts or exchange money.
How to use this bmi calculator
Enter your measured height and weight. BMI uses the same formula for adults of all sexes; age confirms that the adult reference categories apply.
How the calculation works
Convert weight to kilograms and height to meters. BMI = weight ÷ height². The international pound equals 0.45359237 kg and the inch equals 2.54 cm.
For adults 20 and older, CDC categories use thresholds at 18.5, 25, 30, 35 and 40. The displayed reference weight interval is 18.5 × height² to below 25 × height²; it is not a personal goal.
Worked example
At 70 kg and 175 cm, BMI is 70 ÷ 1.75² = 22.86. This falls in the adult healthy-weight BMI category. The corresponding BMI 18.5-to-below-25 weight interval is approximately 56.7 to below 76.6 kg.
Limits and assumptions
For adults aged 20 and older. BMI does not distinguish muscle from fat or assess individual health. The reference interval is not a recommended personal weight. Children, teens, pregnancy and clinical body-composition assessment need different interpretation.
Frequently asked questions
Can I enter feet and inches?
Yes. With Imperial selected, enter total inches or a form such as 5 ft 9 in. Metric mode uses centimeters. The weight field follows pounds or kilograms.
Do male and female adults use different BMI formulas?
No. The adult formula and category thresholds are the same. Other health assessments may consider factors that BMI does not.
Why can a rounded BMI appear on a category boundary?
The category uses the full calculation. A value just below 25 can round to 25.00 on screen; the unrounded calculation remains below the boundary.
Can this calculate a child’s BMI percentile?
No. Children and teens require sex- and age-specific growth references, which are not part of this adult tool.