Calculate your Body Mass Index from height and weight — metric or imperial.
BMI is a general screening measure and doesn't account for muscle mass, bone density, or body composition. It isn't a diagnosis.
Body Mass Index (BMI) is a simple screening measure calculated from your height and weight, using the standard formula weight (kg) ÷ height (m)². It's widely used by health organizations as a quick, population-level indicator of whether someone's weight falls into a typical range for their height — not as an individual diagnosis. This calculator accepts either metric (kg/cm) or imperial (lb/ft-in) units and instantly shows both your BMI number and which standard WHO category it falls into.
Choose Metric or Imperial units, enter your height and weight, then tap Calculate BMI to see your Body Mass Index and its standard category.
BMI equals weight in kilograms divided by height in metres squared. For a person who weighs 70 kg and is 175 cm tall, that is 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625, or about 22.9, which falls in the normal range. With imperial units the equivalent formula is 703 × weight in pounds ÷ height in inches squared: 154 lb at 5 ft 9 in (69 in) gives roughly 22.7. This tool does the conversion for you, so you can enter feet and inches or centimetres, whichever you know.
These are the standard WHO adult categories. They describe populations, so treat the number as a starting point for a conversation, not a verdict about your health.
BMI cannot tell muscle from fat. A strength athlete can land in the overweight range with a low body-fat percentage, while someone with little muscle can sit in the normal range yet carry more body fat than is healthy. It also does not reflect where fat is stored, age-related changes, or differences between ethnic groups, and standard adult cut-offs do not apply to children and teenagers, who are assessed with age- and sex-specific growth charts. If your result worries you, or you are making health decisions, talk to a doctor or dietitian. Pair it with other checks such as waist measurement and blood tests. You may also find the Age Calculator and Unit Converter useful for converting between kilograms, pounds and stones.
What do the BMI categories mean?
Under 18.5 is Underweight, 18.5–24.9 is Normal weight, 25–29.9 is Overweight, and 30+ is Obesity, using the standard WHO ranges.
Is BMI accurate for everyone?
BMI is a general screening measure and doesn't account for muscle mass, bone density, or body composition — it isn't a diagnosis.
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