Formulas: Metric: BMI = weight (kg) / (height (m))². US Imperial: BMI = 703 × weight (lbs) / (height (inches))².
Body Mass Index (BMI) is a standard, widely-used screening tool that estimates whether a person is underweight, normal weight, overweight, or obese based on their height and weight.
The BMI Calculator allows you to easily input weight in kilograms or pounds and height in centimeters or feet and inches. It then processes these numbers to give you a clear BMI score corresponding to standard classifications.
While BMI is a useful general guide for assessing weight-related health risks, it has some limitations. For example, it does not directly measure body fat percentage and may overestimate body fat in muscular athletes or underestimate it in older individuals who have lost muscle mass.
Our tool provides a transparent breakdown: you can see your calculated score side-by-side with the official classifications defined by the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC).
Whether you are setting personal weight goals, checking health guidelines, or tracking changes, this calculator operates completely in the browser for speed and privacy.
Example inputs and outputs using the calculator logic.
Quick links to similar calculators.
Answers to help you use the calculator correctly.
A healthy BMI range for adults is typically 18.5 to 24.9. Under 18.5 is considered Underweight, 25 to 29.9 is Overweight, and 30 or above is Obese.
Muscle is much denser than fat. A muscular person or athlete may have a high BMI that classifies them as overweight or obese, despite having low body fat. In these cases, waist-to-height ratio or skinfold tests may be more accurate.
Yes, the standard formula is identical for men and women. However, body fat distributions can differ by sex and age, so clinicians often interpret the results alongside other metrics.
For children and teens, BMI is calculated using the same formula but is plotted on percentile charts that account for age and sex, since body composition changes rapidly during growth.