Body Mass Index — find out if you're in a healthy weight range
BMI, or Body Mass Index, is a numerical value calculated from your height and weight. It was developed in the early 19th century by Belgian mathematician Adolphe Quetelet and has since become one of the most commonly used indicators in health and wellness assessments worldwide.
The formula is straightforward:
Metric: BMI = Weight (kg) ÷ Height (m²) Imperial: BMI = 703 × Weight (lbs) ÷ Height (in²)
Although BMI is not a direct measure of body fat, it provides a useful general reference point that doctors, fitness professionals, and public health organizations use as part of broader health evaluations.
Once you calculate your BMI, the result falls into one of the following standard categories defined by the World Health Organization (WHO):
Underweight — BMI below 18.5 A BMI under 18.5 may suggest that your body isn’t getting enough nutrition or that there could be underlying health concerns. People in this range are sometimes at risk for nutrient deficiencies, weakened immunity, and bone loss.
Normal Weight — BMI 18.5 to 24.9 This range is generally associated with a lower risk of weight-related health problems. If your BMI falls here, it typically indicates a healthy balance between your height and weight.
Overweight — BMI 25 to 29.9 A BMI between 25 and 29.9 may indicate excess weight for your height. While it doesn’t automatically mean poor health, it can be a signal to pay closer attention to diet, activity levels, and lifestyle habits.
Obese — BMI 30 and above A BMI of 30 or higher is classified as obese and is associated with a higher risk of conditions like type 2 diabetes, heart disease, high blood pressure, and sleep apnea. Further subcategories include Class I (30–34.9), Class II (35–39.9), and Class III (40+).
Using our BMI Calculator is quick and easy. Here’s how:
No complicated steps, no account required. Just accurate results in a matter of seconds.
Tracking your BMI regularly can help you:
Health professionals across the globe use BMI as a starting point during routine check-ups and wellness screenings. While it’s not a diagnosis on its own, it is a valuable data point that helps paint a broader picture of your overall health.
It’s important to understand that BMI has limitations. Because it only considers height and weight, it does not account for:
Muscle mass: Highly muscular individuals such as athletes may have a high BMI despite having very low body fat.
Fat distribution: BMI doesn’t reveal where fat is stored in the body. Belly fat, for example, carries different health implications than fat stored in other areas.
Age and sex differences: Body composition naturally changes with age, and men and women tend to carry fat differently. These nuances are not reflected in a standard BMI reading.
Ethnicity: Some research suggests that certain ethnic groups face health risks at lower BMI thresholds than others.
For this reason, BMI is best used alongside other assessments such as waist circumference measurements, body fat percentage tests, blood work, and professional medical advice.
For children and adolescents aged 2 to 19, BMI is calculated the same way as for adults, but it is interpreted differently. Instead of fixed thresholds, a child’s BMI is compared against age- and sex-specific growth charts to determine their BMI-for-age percentile.
The categories for children are:
Always consult a pediatrician for a complete assessment of a child’s growth and development.
Whether your BMI is in the healthy range or not, these general tips support long-term weight and wellness management:
Eat a balanced diet rich in whole foods, vegetables, lean proteins, and healthy fats. Minimize processed foods, added sugars, and excessive sodium.
Stay physically active with at least 150 minutes of moderate aerobic activity per week, as recommended by the WHO.
Stay hydrated — drinking adequate water supports metabolism and helps manage appetite.
Prioritize sleep — poor sleep is closely linked to weight gain and metabolic disruption.
Manage stress — chronic stress triggers cortisol release, which is associated with increased fat storage, especially around the abdomen.
Consult a professional — for personalized guidance, speak with a registered dietitian, certified fitness trainer, or your primary care physician.
The BMI Calculator on this page is intended for informational and educational purposes only. Results are based on the standard WHO BMI formula and should not be considered medical advice. Always consult a qualified healthcare professional before making decisions about your diet, exercise, or health.
BMI is a useful general screening tool, but it has limitations, especially for athletes, older adults, pregnant women, and certain ethnic groups. It should be considered alongside other health indicators.
Checking your BMI once every few months is generally sufficient for tracking trends over time. Daily fluctuations in weight are normal and don’t necessarily reflect true changes in body composition.
A healthy BMI for adult women, as with adult men, falls between 18.5 and 24.9 according to standard WHO guidelines. However, women tend to have a higher body fat percentage than men at the same BMI, so additional assessments may be helpful.
The standard healthy BMI range for adult men is also 18.5 to 24.9. Men generally carry more muscle mass, so a BMI at the higher end of this range may still represent a healthy body composition.
BMI is associated with increased risk for several chronic conditions at higher ranges, but it cannot predict or diagnose disease on its own. It is one data point among many used in health assessments.