BMI Calculator
Calculate Body Mass Index from height and weight using metric or imperial units. The result is a general screening value and should not be treated as a diagnosis.
Calculate Your BMI
Choose your unit system, enter height and weight, then calculate your BMI.
What Is BMI?
BMI stands for Body Mass Index. It is a numerical value calculated from a person's weight and height and is commonly used as a general screening measure for adults.
BMI can be useful as one piece of information, but it does not directly measure body fat, muscle mass, fitness or overall health.
BMI Formula
Height must be converted to meters when using the metric formula. The height is then squared before dividing the weight by it.
Example BMI Calculation
Suppose an adult weighs 70 kg and is 175 cm tall.
BMI: 70 ÷ (1.75 × 1.75)
BMI ≈ 22.9
General Adult BMI Categories
| BMI | General Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to 24.9 | Healthy weight |
| 25.0 to 29.9 | Overweight |
| 30.0 or higher | Obesity |
These are commonly used adult screening ranges. They should not automatically be applied to children and adolescents.
BMI Using Imperial Units
BMI can also be calculated using pounds and inches.
The calculator converts the imperial measurements into the standard BMI scale automatically.
Why BMI Has Limitations
BMI uses only height and weight. It does not distinguish between muscle and fat, so two people with the same BMI can have different body compositions.
BMI also does not describe where body fat is distributed or provide a complete picture of fitness or overall health.
BMI and Muscle Mass
People with higher muscle mass may have a higher BMI because muscle contributes to body weight. BMI does not separately measure muscle mass.
BMI for Children and Teenagers
Adult BMI categories should not simply be used for children or adolescents. Growth changes with age, so age- and sex-specific approaches may be used instead.
Common BMI Calculator Mistakes
- Entering pounds when kilograms are expected.
- Entering centimeters where meters are expected.
- Entering the wrong height.
- Applying adult categories to children.
- Treating BMI as a diagnosis.
- Using BMI as the only measure of health.
How to Use This BMI Calculator
- Choose Metric or Imperial.
- Enter your weight.
- Enter your height.
- Select Calculate BMI.
- Review the BMI result and general category.
When Should You Seek Professional Guidance?
If you have concerns about your weight, nutrition, growth, body composition or other health issues, individualized guidance from a qualified healthcare professional may be appropriate.
A calculator can provide a general number, but it cannot take the place of a full health assessment.
BMI Calculator FAQ
Common questions about BMI calculations.
BMI stands for Body Mass Index. It is a numerical value calculated from height and weight.
No. BMI is a general screening measure and is not a diagnosis by itself.
Yes. Select the Imperial option and enter weight in pounds and height in feet and inches.
Yes. BMI does not distinguish muscle from fat, so it may not fully represent body composition.
Adult BMI categories should not simply be applied to children and adolescents.
No. BMI is only one general screening measure and does not provide a complete assessment of health.