What BMI Means
Body Mass Index, or BMI, is a simple height-to-weight screening measure. It is commonly used to sort adult results into broad categories such as underweight, normal weight, overweight, and obesity.
BMI Ranges and Healthy Weight
A commonly used adult healthy BMI range is about 18.5 to 25. This calculator also shows the corresponding healthy weight range for the height you enter, which helps connect the BMI result to a more practical target range.
Metric and Imperial BMI
You can use either metric or imperial measurements. Enter height in cm or ft/in and weight in kg or lb. The calculator converts the values automatically and returns the same BMI result.
BMI Limitations
BMI is a screening estimate, not a diagnosis. It does not directly measure body fat, muscle mass, or body composition, so it can be less informative for athletes, pregnant people, some older adults, and children or teens. For under-18s, BMI is usually interpreted with age- and sex-specific percentiles.
BMI Calculator FAQ
What is BMI?
BMI, or Body Mass Index, is a screening measure that relates body weight to height. It is commonly used to estimate whether weight is low, normal, high, or very high for a given height.
How do you calculate BMI?
The standard formula is BMI = weight (kg) / height (m)^2. This calculator accepts both metric and imperial inputs and converts them automatically before calculating the result.
What is a normal BMI range?
A commonly used adult normal BMI range is about 18.5 to 25. This calculator also shows an estimated normal weight range for the entered height.
What is the difference between BMI and the new BMI?
The calculator shows both the traditional BMI and the new BMI. The newer version adjusts the formula to reduce some of the height-related distortion in the original BMI formula, especially for very short or very tall people.
Is BMI always accurate?
No. BMI is a useful screening estimate, but it does not directly measure body fat, muscle mass, age, or body composition. It can be less informative for athletes, older adults, pregnant people, and some children or teens.
Can I use feet, inches, pounds, kilograms, and centimeters?
Yes. You can enter height in cm or ft/in and weight in kg or lb. The calculator keeps the values synchronized both ways.
Is BMI the same for men and women?
The standard adult BMI formula is the same for men and women, but BMI still does not capture differences in body composition, muscle mass, or fat distribution.
Should children and teens use an adult BMI calculator?
Not directly. For children and teens, BMI is usually interpreted using age- and sex-specific percentiles rather than standard adult BMI category cutoffs.
