BMI Calculator
Enter height and weight in metric or imperial units. You’ll see your body mass index, its WHO category and the weight range that counts as healthy for your height.
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BMI is a rough screening number, not a diagnosis or medical advice. It doesn’t distinguish muscle from fat or account for age, sex, ethnicity or where weight is carried. These adult ranges don’t apply to children and teenagers under 20 (who use age- and sex-specific percentiles) or during pregnancy. Talk to a clinician about your own health.
How BMI is calculated
Body mass index is weight in kilograms divided by height in metres squared. In imperial units it’s 703 × weight in pounds ÷ height in inches squared. Someone 175 cm tall weighing 72 kg has a BMI of 72 ÷ 1.75² = 23.5.
The World Health Organization classes an adult BMI of 18.5–24.9 as healthy weight, 25–29.9 as overweight and 30 or more as obesity, with subclasses shown in the table. Some health bodies use lower cut-offs for people of Asian descent (overweight from 23, obesity from 27.5) because risk rises at lower BMIs.
BMI Prime is your BMI divided by 25, the top of the healthy range, so 1.00 is the upper limit and 0.74 the lower. The healthy weight range is simply the weights that give a BMI of 18.5 to 24.9 at your height.
Questions
What is a healthy BMI?
For adults, 18.5 to 24.9. Below 18.5 is classed as underweight, 25 to 29.9 as overweight and 30 or above as obesity. These are population screening ranges; a doctor looks at much more than BMI.
Is BMI accurate for athletes or older adults?
Often not. Muscle is denser than fat, so muscular people can score as overweight while being lean. Older adults may lose muscle and score “healthy” while carrying more fat. Waist measurement and body composition tests add context.
Can I use this BMI calculator for children?
No. Children and teens (ages 2–19) are assessed with BMI-for-age percentiles that depend on age and sex. Use a pediatric BMI percentile calculator or ask a pediatrician.
How do I calculate BMI in pounds and inches?
Multiply weight in pounds by 703, then divide by height in inches squared. At 5 ft 9 in (69 in) and 160 lb: 160 × 703 ÷ 69² = 23.6.