There are two main ways to calculate body fat: Home Body Fat Scales. Skinfold Calipers (Callipers).

Body fat scales: Claim to measure body fat quickly and conveniently.

These body fat scales use the Bioelectrical Impedance method to measure your body fat percentage.

 A low-level electrical current is passed through your body and the "impedance", or opposition to the flow of current, is measured. The result is used in conjunction with your weight and other factors to determine your body fat percentage.

Unfortunately, your body's "impedance level" can be altered by many factors besides body fat. For instance, the amount of water in your body, your skin temperature and recent physical activity can all adversely affect the results. So only by following strict rules can you hope to get an accurate measurement of your body fat using these scales.

Measuring body fat: With a set of body fat calipers is the most cost effective way to determine fat levels. But it's important to use them correctly.

For instance, either have a professional take the measurements for you or buy a set of Accumeasure calipers (callipers) and follow the measuring instructions.

Accumeasure are the only calipers than allow you to test yourself and most studies have shown that they are very accurate.