Body Mass Index (BMI) is a numerical value calculated from a person's weight and height. It is widely used as a screening tool to categorize adults into weight groups — underweight, normal weight, overweight, and obese — and to identify potential health risks associated with being over or underweight.
While BMI is a useful starting point, it does not directly measure body fat or distinguish between muscle and fat mass. Athletes and highly muscular individuals may have a high BMI without excess body fat. It's best interpreted alongside other health assessments such as waist circumference and blood pressure.
How to Use the BMI Calculator
1Choose your unit system: Metric (kg/cm) or Imperial (lbs/ft/in).
2Enter your weight and height.
3Click Calculate BMI.
4View your BMI score, weight category, and the healthy weight range for your height.
According to the WHO, a BMI between 18.5 and 24.9 is considered a healthy normal weight. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese.
BMI is a useful screening tool but has limitations. It may overestimate body fat in muscular athletes and underestimate it in older adults who have lost muscle mass. It also does not account for differences in body composition by age, sex, or ethnicity.
Yes. For children and teens aged 2–19, BMI is interpreted using age- and sex-specific growth chart percentiles rather than fixed cutoffs. This adult calculator is not appropriate for children.
The healthy weight range is based on a BMI of 18.5–24.9. You can calculate it as: min weight = 18.5 × height² (m²) and max weight = 24.9 × height² (m²). The calculator shows this range in the results.
BMI is a starting point for understanding your weight status. If your BMI is outside the healthy range, consult a healthcare provider for personalized guidance on diet, exercise, and lifestyle changes.