One of the simplest ways is to use a caliper. You can usually find these at your local sporting goods/fitness shop. If you can’t find them locally, you can order them off the internet. Calipers measure the thickness of a skin fold on your triceps. Then there are directions that come with the caliper that show you how to use the number you get to derive your body fat %.If you don’t want to go out and buy some calipers, there is a body fat % calculator on my website. The calculator uses the circumference of several parts of your body and then plugs them into a formula developed by the U.S. Navy to derive an approximation of your body fat %.