BMI Calculator
Calculate your Body Mass Index (BMI) using US customary or metric units.
How this BMI calculator works
Select your preferred unit system and enter your height and weight. The calculator applies the standard adult BMI formula to determine your BMI value and displays the corresponding weight category.
BMI categories for adults
| Category | BMI range |
|---|---|
| Underweight | Below 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obesity class I | 30.0 – 34.9 |
| Obesity class II | 35.0 – 39.9 |
| Obesity class III | 40.0 and above |
BMI formulas
Height is converted to inches and multiplied by the BMI factor 703.
Height is converted from centimeters to meters.
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FAQ
What does BMI mean?
BMI (Body Mass Index) is a numerical value calculated from your height and weight. It is commonly used as a general indicator to assess weight status in adults.
Can BMI be used for children or teenagers?
BMI is primarily intended for adults aged 18 and older. Children and teenagers use different age- and sex-specific BMI charts because their bodies change as they grow.
Is BMI accurate for everyone?
BMI is a general guideline and may not be accurate for everyone. It does not account for factors such as muscle mass, body composition, age, or sex.
Why is BMI commonly used?
BMI is widely used because it provides a quick and simple way to relate weight to height using only two measurements. It is often applied in health screenings and general guidance for adults.
What BMI ranges are considered underweight or overweight?
For adults, a BMI below 18.5 is considered underweight, 18.5–24.9 is normal weight, 25.0–29.9 is overweight, and 30.0 or higher falls into obesity categories.
Can I switch between US and metric units?
Yes. This BMI calculator allows you to switch instantly between US customary and metric units without manually converting your height or weight.