The Boys' Growing Up in the Lord

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Body Fat Estimation for Men

Calculator 1: BMI based

This calculator uses your BMI (Body Mass Index) to estimate the percentage of your body fat. It isn't highly accurate because it cannot distinguish a person who is very athletic from a couch potato, but still, it isn't bad. The accuracy is supposed to be within 4.5% of the actual body fat value.


Your Height: inches centimeters
Your Weight: pounds kilograms
Your Age:


Your BMI is and your estimated body fat is %.

Interpreting the BMI:

BMI Classification
18.5 or less Underweight
18.5 to less than 25 Normal Weight
25 to less than 30 Overweight
30 to less than 35 Mildly Obese
35 to less than 40 Obese
40 or greater Morbidly Obese


Interpreting the body fat estimate:

Classification Body Fat %
Athletes 6–13%
Fit 14–17%
Average 18–24%
Obese 25%+

Calculator 2: Measurement Based

I have not found a comparison to say how accurate this estimate is.

Your Waist (measured at the naval): inches centimeters
Your Weight: pounds kilograms

Your estimated body fat is %.