Calculate body mass index from height and weight using metric or imperial units. The category shown is for adults aged 20 and older.
Adult BMI calculator
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What the result means
The standard adult BMI ranges are below 18.5 (underweight), 18.5 to below 25 (healthy weight), 25 to below 30 (overweight), and 30 or higher (obesity). The category uses the unrounded result. See the CDC’s adult BMI categories.
Formula and example
BMI = weight in kilograms ÷ height in metres squared. For 70 kg and 175 cm, the calculation is 70 ÷ 1.75² = 22.86. Imperial entries are converted using 1 inch = 2.54 cm and 1 pound = 0.45359237 kg before the same calculation.
When BMI is less useful
BMI is a screening measure, not a diagnosis or a direct measurement of body fat. It does not distinguish muscle from fat. A clinician considers other health information alongside it. Children and teenagers need age-specific assessment rather than these adult categories. Pregnancy also requires a different clinical interpretation. Read the CDC’s explanation of BMI limitations.
Do not use this number alone to decide on treatment or a weight-change plan. Discuss personal health questions with a qualified healthcare professional.
