What is BMI?
Body Mass Index (BMI) is a simple screening number that compares your weight to your height. It's calculated as weight (kg) ÷ height (m)². Because it's quick and requires no special equipment, it's widely used as a first check of whether someone is in a healthy weight range.
BMI categories
Under 18.5 is considered underweight, 18.5–24.9 healthy weight, 25–29.9 overweight, and 30 or above obese. The healthy-weight range shown is the weight that would put your BMI between 18.5 and 24.9 for your height.
Frequently asked questions
Is BMI accurate?
BMI is a useful population-level screening tool but has limits for individuals. It doesn't account for muscle mass, body composition, age or sex, so athletes and some body types can be misclassified. Use it as a rough guide alongside other health measures.
What is a healthy BMI?
A BMI between 18.5 and 24.9 is generally considered healthy for adults. This tool shows the exact weight range that corresponds to a healthy BMI for your height.