How can I calculate my BF%?
Here's how the navy does it:
Basically, use your height and measurements of a couple body parts in a formula to arrive at a estimate.
Use the following formulas to calculate your estimated body fat percentage:
You can buy some calipers and measure it yourself. There a sophisticated machines and even bathroom scales that claim to be able to measure body fat. The most accurate would probably be the hydrostatic submersion test.
My favorite way is looking in a mirror.
We have a nice reference page on how to calculate your body fat percentage and the pluses and minuses of each method. Here is a summary.
BIA - The simplest method is hopping on a BIA, bioimpedance analysis, monitor. The limitations: you need a monitor that measures both the upper and lower body, not just one or the other. The readings vary by hydration and water retention levels. To get the most accurate readings take them at the same time of day before eating and after voiding. Because they send a weak current thru you, people with cardiac pacemakers or who are pregnant should not use them.
Skinfold - Another easy method is using the Accumeasure, an inexpensive skin caliper that you use on yourself. With practice you can get reproducible readings at the supra-iliac site and find your body fat percentage by looking up the corresponding mm on Accumeasures chart that takes age and gender into account.
Alternatively, you can have a trained tester take skin fold measurements at several body sites to calculate your body fat percentage.
The Formula Method involves taking circumference measurements at various body sites depending on your gender and applying a formula. Different formulas involve different measurement requirements.
The above methods are the easiest and most affordable ways to monitor your body fat percentage on an ongoing basis. The following are highly accurate, but more expensive and require finding a facility that offers them making them less suitable for ongoing monitoring your progress of your body composition.
The Dexa Dual Energy X-Ray Absorptiometry Test is probably the most accurate, but it does use X-rays even if radiation exposure is low. It is costly and not practical for repeat measurement to determine your progress.
Underwater Weighing, although highly accurate, depends on ones ability to expel air from the lungs while submerged under water. Results also depend on hydration levels. This method can be expensive and cumbersome to use for ongoing body fat monitoring.
The newer Bod Pod method is an air chamber and is similar to the underwater weighing method, however, it uses air displacement rather than water displacement making it more convenient. The same factors apply as far as hydration levels affecting the results. As the popularity of this method increases, it is easier to find a facility in your area.
There are several ways to measure your body fat percentage.