BMI Calculator
Calculate your Body Mass Index from height and weight, in metric or imperial units, with your category.
Last reviewed July 1, 2026
Educational estimate only — not medical advice. Consult a healthcare professional about your health.
Body Mass Index (BMI) is a quick screening number that relates your weight to your height. It's widely used by health services as a rough indicator of whether someone is in a healthy weight range for their height. This calculator works in both metric and imperial units and shows your BMI category.
BMI is a general guide, not a diagnosis. It doesn't distinguish muscle from fat, so very muscular people can read as 'overweight' while the number can understate risk for others. Treat it as one data point among many, and talk to a healthcare professional about your individual health.
BMI categories
For adults, the World Health Organization ranges are: below 18.5 = underweight; 18.5–24.9 = healthy weight; 25.0–29.9 = overweight; 30.0 and above = obese.
These ranges are for adults and are not appropriate for children, pregnant people, or athletes. Some populations have different risk thresholds, which is why clinicians consider BMI alongside other measures.
How BMI is calculated
The formula is weight in kilograms divided by height in metres squared: BMI = kg ÷ m². In imperial units it's 703 × pounds ÷ inches². This calculator handles the conversion for you whichever units you choose.
Frequently asked questions
▶Is BMI accurate?
BMI is a useful population-level screening tool but a blunt instrument for individuals. It can't tell muscle from fat or where fat is stored, so use it as a rough guide alongside other measures and professional advice.
▶What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered the healthy range. This is a general guideline, not a personal medical assessment.
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Disclaimer: BMI Calculator results are estimates for general information and education only, and are not financial, tax, legal or medical advice. Verify important decisions with a qualified professional.