For example, at age 30, the 'healthy' range is calculated to be 14.8 to 23.4, and at 40, that range is 13.7 to 22.2, thus allowing very severely underweight individuals (below 15) be considered 'healthy,' while a significant portion of the upper healthy range is considered 'overweight.' Even worse, if you consider elderly people, say 70, they are calculated to have a healthy body fat percentage with a BMI of 10.2 to 18.8, which means that only the lowest 4 healthy BMI numbers (18.5-18.8) are considered healthy by that age, and people are allowed to go down to dangerous BMIs as low as 10.2. However, as you get older, the range that is considered healthy gets lower and lower. For my age, 18, it says a healthy BMI (6.0% - 17.9% body fat) would be from 16.2 to 24.7, which is not that far off from the 18.5-24.9 range, although it allows for people who are anorexic (below 17.5) or near severely underweight (almost below 16) to be considered to have an athletic body fat percentage, in other words, healthy. The heritage BMI to Body Fat Calculator seems to be more inaccurate than BMI, considering it is actually telling people to go lower than even BMI does. Keep in mind that all of these equations, like anything else, have some general limitations:

Based on that information, I can get a pretty good idea of what my body fat percentage really is. Personally, I like to try all the methods and see what the average value and the range are. Yet others swear by Covert Bailey's method. However, most people will likely tell you that the Department of Defense Method or the YMCA Method is the most accurate. I couldnt find a site that actually explains these equations, but I can make some educated guess. It is recommended that you use the same device to measure and track your body fat percentage and check the trends in the change of weight loss and muscle.

For me, the most accurate method was the Modified YMCA Method. According to WikiHow, the Navys Body Fat calculation formulas are as follows (measurements in cm): men: Fat 86.010LOG (abdomen - neck) - 70.041LOG (height) + 30.30. In reality, there are many more variables that affect body fat percentage than just the simple things that are being measured for these equations. It must be noted that no empirical formula is perfect. I was surprised to find that the YMCA Method was less accurate than the Heritage Method. The Modified YMCA Method was the most accurate for my body with the Department of Defense Method trailing close behind it. It's interesting to note that all of the methods are within the expected +/- 3%.

Us navy body fat calculator accuracy