Functional Strength Lab‘s BMI Calculator allows you to determine your BMI by simply inputting your height and weight in the shaded boxes below.

The formula underlying the BMI calculator is based on the formula found on the CDC‘s and many other websites.

The formula is:

- Weight in pounds/((Height in inches * Height in inches))*703.

— ** The 703 is a constant used to correct for this formula being in inches (in) and pounds (lbs) instead of the original formula’s kilograms (kg) and centimeters (cm).** —

Please note that while the BMI is a widely used predictive metric of health, this does not mean that it is without its own detractors and controversies. Some of the issues revolving around the use of the BMI calculation include:

- The calculation was devised in the early 1800’s. Average body sizes varied from that time to present, and advances in nutrition and weight training enable many “healthy” individuals to fall within the “Overweight” or “Obese” categories. These terms carry with them an “unhealthy” connotation.
- Other methods are available for measuring a more critical, wellness-predictive metric — body composition– or body fat %. Skin fold testing, water displacement, and electric current testing are all options that could provide a more accurate view of one’s health. While the BMI is not considered a “body composition” test, this argument is brought up frequently when the BMI is used to calculate “overall health,” or perhaps more importantly to some — the premium for an individual health plan.
- The BMI calculator has a changing and non-agreed-upon standard for where “Overweight” and “Obese” begin among various health governing organizations.
- In terms of other informal and cheap health predictive testing there appears to be a much more statistically accurate (predictive) model: the waist circumference-to-height ratio.

Regardless of these controversies, the reasons for the BMI’s longevity of use include:

- It is a cheap and non-tool-intensive method for predicting future health problems with some degree of accuracy (accuracy varies depending upon who you ask.)
- Requires minimal skill or training to calculate properly when compared to other health predictive tests.
- Inertia. It has been in place and used since the 1800’s.

Wherever you stand on the issue doesn’t matter to us. We just want to make it easier for our users to calculate their BMI if they so choose. Enjoy!