BMI Calculator
Calculate your Body Mass Index (BMI) using your height and weight. Choose metric or imperial units and get your result instantly in your browser.
What is a BMI Calculator?
A BMI Calculator uses your height and weight to calculate your Body Mass Index (BMI). BMI is a commonly used screening measure for adults that can help classify weight status into categories such as underweight, normal weight, overweight, and obesity.
BMI is calculated by dividing weight in kilograms by height in meters squared. The same calculation can be performed using pounds and inches with the appropriate conversion factor. This BMI Calculator supports both metric and imperial measurements so you can use the system you are most comfortable with.
How to use the BMI Calculator
Enter your height and weight, choose your preferred measurement system, and the calculator will display your BMI and its corresponding category.
- Choose Imperial (lb / in) or Metric (kg / cm).
- Enter your weight in the selected unit.
- Enter your height in the selected unit.
- Click Calculate BMI or enter both values to see the result automatically.
- Review your BMI value and the corresponding category.
BMI categories for adults
For adults, commonly used BMI categories are based on the following ranges:
- Underweight: BMI below 18.5
- Normal weight: BMI from 18.5 to 24.9
- Overweight: BMI from 25.0 to 29.9
- Obesity: BMI of 30.0 or higher
These ranges are general adult screening categories. BMI does not directly measure body fat, and the same BMI can represent different amounts of body fat and lean mass in different people. :contentReference[oaicite:3]{index=3}
How BMI is calculated
The BMI calculation depends on the measurement system you choose.
- Metric: BMI = weight (kg) ÷ height (m)²
- Imperial: BMI = weight (lb) ÷ height (in)² × 703
If you enter your height in centimeters, the calculator converts it to meters before performing the metric calculation.
What are the limitations of BMI?
BMI is useful as a general screening measure, but it does not provide a complete picture of an individual's health. It does not directly measure body fat, muscle mass, or where body fat is distributed.
For example, people with substantial muscle mass may have a higher BMI without having a high level of body fat. BMI can also be interpreted differently in children and adolescents, where age- and sex-specific measures are used rather than standard adult categories. :contentReference[oaicite:4]{index=4}
For these reasons, a BMI result should not be treated as a diagnosis. If you have concerns about your weight or health, consider discussing your results with a qualified healthcare professional.
Frequently Asked Questions (FAQ)
BMI can provide a useful general screening measure for adults, but it does not account for body composition or fat distribution. People with high muscle mass, for example, may have a higher BMI without having excess body fat.
A BMI from 18.5 to 24.9 is commonly classified as normal weight for adults. BMI categories are screening ranges rather than a diagnosis of an individual's health. :contentReference[oaicite:5]{index=5}
No. This calculator uses standard adult BMI categories. BMI interpretation for children and adolescents requires age- and sex-specific growth references, so a child should be assessed using an appropriate pediatric BMI tool. :contentReference[oaicite:6]{index=6}
No. The calculation is performed directly in your browser using JavaScript. The tool does not need to send your height or weight to a server to calculate your BMI.
There is no single schedule that is appropriate for everyone. BMI is most useful when considered as part of a broader view of health rather than as a measurement that needs to be checked frequently.
For additional information about BMI and adult weight categories, see the World Health Organization (WHO) guidance on BMI .