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BMI Calculator

Knowing your BMI is the best way to gauge your standing with increased risk factors for heart disease, hypertension, diabetes, and osteoarthritis! This measure of your weight should be combined with your hip to waist ratio measurement to give you the best idea of your level of risk. Normally, to determine your BMI, weight in kilograms is divided by height in meters squared.


You may also consider having your physician perform a body fat analysis, which may be easily performed in the office with a handheld or scale based instrument!



Overweight refers to increased body weight in relation to height, when compared to some standard of acceptable or desirable weight. NOTE: Overweight may or may not be due to increases in body fat. It may also be due to an increase in lean muscle. For example, professional athletes may be very lean and muscular, with very little body fat, yet they may weigh more than others of the same height. While they may qualify as "overweight" due to their large muscle mass, they are not necessarily "over fat," regardless of BMI. Individuals with a BMI of 25 to 29.9 are considered overweight.


Obesity is defined as an excessively high amount of body fat or adipose tissue in relation to lean body mass. The amount of body fat (or adiposity) includes concern for both the distribution of fat throughout the body and the size of the adipose tissue deposits. Body fat distribution can be estimated by skinfold measures, waist-to-hip circumference ratios, or by a body fat analysis. Individuals with a BMI of 30 or more are considered obese.

Note for children:
BMI is age and gender specific.  Because BMI changes substantially as children get older, BMI-for-age is the measure used for children ages 2 to 20 years. BMI-for-age is plotted on growth charts by healthcare professionals - ask yours to review your child's weight and height for his age.

Body Mass Index Web Calculator




These calculators require a JavaScript-enabled Web browser to operate. Alternately, you may make use of the mathematical formulas at the bottom of this page.

English Calculation

Height: feet
and inch(es)

Weight: lbs.

Your BMI:

Metric Calculation

Height: m
(example: 175cm = 1.75m)

Weight: kg

Your BMI:


How to Mathematically Calculate Body Mass Index (BMI)

English Formula:

BMI = [Weight in pounds Height in inches Height in inches] x 703

Fractions and ounces must be entered as decimal values.

Fraction Ounces Decimal
1/8 2 .125
1/4 4 .25
3/8 6 .375
1/2 8 .5
5/8 10 .625
3/4 12 .75
7/8 14 .875


Example: A 33 pound 4 ounce child is 37 5/8 inches tall

33.25 pounds divided by 37.625 inches, divided by 37.625 inches x 703 = 16.5

Metric Formula:

BMI = Weight in kilograms [Height in meters]2


BMI = [Weight in kilograms Height in cm Height in cm] x 10,000

Example: A 16.9 kg child is 105.2 cm tall.

16.9 divided by 105.2 cm divided by 105.2 cm x 10,000 = 15.3 BMI

Last revised: December 30, 2004