This calculator will determine Body Mass Index or BMI, given an individual's weight and height. Weight can be entered pounds, stones and pounds, or kilograms. Height can be entered in inches, feet and inches, meters, or centimeters.
BMI is a way of measuring a person's weight relative to his or her height. BMI expresses how thick or thin a person is in simple numeric terms, and allows doctors and other health professionals to discuss weight objectively on a standardized scale.
- Metric units: BMI = weight (kg) ÷ height2 (m)
- US units: BMI = (weight (lb) ÷ height2 (in)) * 703
Example 1 (Calculating BMI in metric units)
Matilda weighs 64 kg and is 1.9 meters tall. What is her BMI?
- BMI = w ÷ h2
- BMI = 64 ÷ 1.92
- BMI = 64 ÷ 3.61
- BMI = 17.7
Example 2 (Calculating BMI in US units)
Stanley weighs 184 lb and is 5 feet, 10 inches tall. What is his BMI?
- 5 feet, 10 inches = 70 inches
- BMI = (w ÷ h2) * 703
- BMI = (184 ÷ 702) * 703
- BMI = (184 ÷ 4900) * 703
- BMI = 0.3755 * 703
- BMI = 26.4
Below is a table of commonly used BMI ranges in North America and Europe for persons aged 21 and older:
Although BMI is calculated the same way worldwide for all ages, the way an individual's BMI is interpreted depending on location and the person's age:
- In many Southeast Asian countries, the thresholds for the overweight and obese categories tend to be lower. For example, in Singapore and Hong Kong a BMI of 23.0 is considered overweight, whereas in the United States a BMI of 25 is considered overweight.
- Children and adolescents are not evaluated using these thresholds at all, but are evaluated relative to others of the same age and gender:
Keep in mind that BMI is a ratio between height and total body weight - it does not differentiate between weight from muscle and weight from fat, nor does it consider an individual's body frame type. BMI is one of several tools used to assess a person's weight and overall health. If you are concerned about your weight, it is best to consult with your doctor or healthcare professional.