Enter your weight and height, and select your preferred units (metric or imperial) to calculate your BMI.
BMI History
What is BMI?
Body Mass Index (BMI) is a simple calculation used to estimate whether a person has a healthy body weight for their height. It’s commonly used by health professionals to screen for weight categories that may lead to health problems.
BMI Formula:
- Metric:
BMI = weight (kg) / height (m²) - Imperial:
BMI = (weight (lbs) / height (in²)) × 703
Although BMI doesn’t directly measure body fat, it provides a quick snapshot of whether your weight is in a healthy range.
How to Interpret BMI Results
Once calculated, your BMI will fall into one of the following categories:
| Category | BMI Range |
|---|---|
| Underweight | Less than 18.5 |
| Normal Weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obesity | 30.0 and above |
These categories are general guidelines. Age, gender, muscle mass, and ethnicity can all influence how BMI should be interpreted. For the most accurate health assessment, always consult with a healthcare provider.
Metric vs. Imperial Units
BMI can be calculated using two unit systems:
- Metric System: Uses kilograms (kg) for weight and meters (m) for height. This is the standard in most parts of the world.
- Imperial System: Uses pounds (lbs) for weight and inches (in) for height. Commonly used in the United States.
Our calculator allows you to choose either system depending on your preference or location, and it will handle the conversion automatically for you.
💬 Frequently Asked Questions (FAQ)
Is BMI accurate?
BMI is a widely used screening tool that gives a general indication of body fat based on weight and height. However, it does not account for muscle mass, bone density, or overall body composition. Athletes, for example, may have a high BMI but low body fat. For a more complete health assessment, consult a healthcare professional.
What is a healthy BMI range?
A healthy BMI typically falls between 18.5 and 24.9. Below 18.5 is considered underweight, 25–29.9 is overweight, and 30 or higher is classified as obesity.
Can I use BMI for children?
BMI for children and teens is interpreted differently. It is age- and sex-specific and compared using percentiles. Pediatricians often use BMI-for-age charts for accurate evaluation.
Why does the calculator ask for metric or imperial units?
Different regions use different measurement systems. The calculator supports metric (kg/m) and imperial (lb/in) so users around the world can accurately check their BMI.