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BMI Calculator
Enter your height and weight in metric or imperial units to see BMI, the standard category and the weight range usually associated with it.
The formula
BMI is weight in kilograms divided by height in metres squared: kg / m². Imperial inputs are converted first (1 lb = 0.45359237 kg, 1 in = 0.0254 m). The WHO adult categories are below 18.5 underweight, 18.5–24.9 normal weight, 25.0–29.9 overweight and 30.0 or above obese.
The healthy weight range shown is the weight that would place you between 18.5 and 24.9 at your height. It is a population reference, not a target prescription.
What BMI does not measure
BMI uses only height and weight, so it cannot distinguish muscle from fat or show where fat is stored. Athletes are often classified as overweight; older adults may have normal BMI with low muscle mass. Body fat distribution, blood pressure, blood glucose and waist circumference carry information BMI does not.
BMI is a screening tool for populations and a rough starting point for a conversation with a clinician. It is not a diagnosis, and it is not designed for children, pregnant people or people with significant edema.
Frequently asked questions
Is BMI accurate for individuals?
It is a rough screening measure, not a body-composition test. Two people with the same BMI can have very different health profiles.
Should children use this calculator?
No. Children and teenagers are assessed with age- and sex-specific BMI percentiles, not the adult categories used here.
Why do athletes often show as overweight?
Muscle is denser than fat, so a muscular person can have a high BMI without excess body fat. BMI cannot tell the difference.
What is a healthy BMI range?
The WHO adult reference is 18.5 to 24.9. The range shown by the calculator is the weight that would put you in that band at your height.
Does it support imperial units?
Yes. Switch to imperial and enter feet, inches and pounds; the result is still reported as BMI.