BMI Calculator

BMI is a measurement of a persons leanness or corpulence based on their height and weight, and is intended to quantify tissue mass. It is widely used as a general indicator of whether a person has a healthy body weight for their height. Specifically, the value obtained from the calculation of BMI is used to categorize whether a person is underweight, normal weight, overweight, or obese depending on what range the value falls between. These ranges of BMI vary based on factors such as region and age, and are sometimes further divided into subcategories such as severely underweight or very severely obese. Being overweight or underweight can have significant health effects, so while BMI is an imperfect measure of healthy body weight, it is a useful indicator of whether any additional testing or action is required. Refer to the table below to see the different categories based on BMI that are used by the calculator.


The Body Mass Index (BMI) Calculator can be used to calculate BMI value and corresponding weight status while taking age into consideration. Use the Metric Units tab for the International System of Units or the US Units tab for pound/ft-inches units.

Height: (in ft and inches)

For Adults

CategoryBMI range - kg/m2
Severe Thinness less than 16
Moderate Thinness 16 - 17
Mild Thinness17 - 18.5
Normal18.5 - 25
Overweight25 - 30
Obese Class I30 - 35
Obese Class II35 - 40
Obese Class IIIgreater than 40

For Children and Teens

CategoryPercentile Range
Underweightless than 5%
Healthy weight 5% - 85%
At risk of overweight85% - 95%
Overweight greater than 95%

Being overweight has its associated risks listed below according to the Centers for Disease Control and Prevention (CDC):

  • High blood pressure
  • Higher levels of LDL cholesterol, which is widely considered bad cholesterol, lower levels of HDL cholesterol, considered to be good cholesterol in moderation, and high levels of triglycerides
  • Type II diabetes
  • Coronary heart disease
  • Stroke
  • Gallbladder disease
  • Osteoarthritis, a type of joint disease caused by breakdown of joint cartilage
  • Sleep apnea and breathing problems
  • Certain cancers (endometrial, breast, colon, kidney, gallbladder, liver)
  • Body pains and difficulty with certain physical functions

Being underweight has its own associated risks listed below according to the Centers for Disease Control and Prevention (CDC):

  • Malnutrition, vitamin deficiencies, anemia (lowered ability to carry blood vessels)
  • Osteoporosis, a disease that causes bone weakness, increasing the risk of breaking a bone
  • A decrease in immune function
  • Growth and development issues, particularly in children and teenagers
  • Possible reproductive issues for women due to hormonal imbalances that can disrupt the menstrual cycle. Underweight women also have a higher chance of miscarriage in the first trimester
  • Potential complications as a result of surgery
  • Generally an increased risk of mortality compared to those with a healthy BMI
  • Weakness