BMI Calculator
Calculate body mass index (BMI) from your height and weight.
Result
General international adult BMI reference
BMI classification may vary by country or medical organization. BMI is a reference indicator and does not replace medical diagnosis.
How It Is Calculated
BMI = weight (kg) ÷ height (m) squaredFor example, 170cm and 65kg gives a BMI of about 22.5.
Reference ranges and rounding
The reference ranges come from CDC's BMI categories for adults aged 20 and older. Using the unrounded BMI, below 18.5 is underweight, 18.5 to below 25 is the normal range, 25 to below 30 is overweight, and 30 or above is the obesity range. These ranges do not diagnose an individual's health.
Categories use the unrounded BMI; only the displayed number is normally rounded to one decimal place. Two decimal places are shown only when rounding would place the displayed number in another category. If two decimals still look like a cutoff, a note states that the actual BMI is below that cutoff. For example, 200cm and 99.8kg is shown as 24.95 and Normal range. Do not make health decisions from BMI alone.
Reading a BMI result
BMI compares weight with height squared and is mainly used as a population-level screening measure for adults. A result near a category boundary should be read as a continuous value, not as a sudden change in health at one decimal point.
What BMI does not measure
BMI does not distinguish muscle from body fat or account for fat distribution, pregnancy, age-related changes, or individual medical history. Children and adolescents require age- and sex-specific growth references rather than the adult categories shown here.
Frequently Asked Questions
How is BMI calculated?
Divide weight in kilograms by height in metres squared: BMI = kg ÷ m².
Can BMI alone determine my health?
No. BMI does not account for every factor such as body composition, age, sex, or individual circumstances. Consult a qualified professional for health decisions.
Do children use the same BMI ranges?
No. Children and adolescents require age- and sex-specific growth references, so these adult ranges should not be applied directly.