Calculating BMI

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.

BMI Formulas

This BMI calculator converts units to satisfy the following BMI formula calculations.

Metric units: BMI = weight (kg) ÷ height² (m)
US units: BMI = (weight (lb) ÷ height² (in)) * 703

Normal Weight Range

Normal weight BMI is 18.5 to 24.9. To calculate your normal weight range use the following:

Metric units:
minimum weight (kg) = 18.5 × height² (m)
maximum weight (kg) = 24.9 × height² (m)
US units:
minimum weight (lb) = (18.5 ÷ 703) × height² (in)
maximum weight (lb) = (24.9 ÷ 703) × height² (in)

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

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:

body mass index for boys 2 to 20 years old

body mass index for girls 2 to 20 years old

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.

References

“Body Mass Index,” Wikipedia, The Free Encyclopedia.
“Healthy Weight,” Centers for Disease Control and Prevention.

source:calculatorsoup

BMI Calculator for Adults