The underwater weight is then plugged into a formula that estimates bodyfat percentage. Unfortunately, the benefits of hydrostatic weighing are largely offset by its inefficiency. The test requires the supervision of highly trained laboratory technicians and can take more than an hour to complete. Because it is so labor intensive, it also is quite expensive. Thus, for most people, hydrostatic weighing is not a viable option.
Skinfold testing is by far the most common method used to measure bodyfat percentage.
Here, folds of skin are pinched at various sites on the body and a caliper is used to measure their thickness. The resultant numbers are added together and then compared to a chart that estimates your bodyfat level. When done correctly, this method is almost as precise as underwater weighing and is much more efficient. However, while the skinfold technique can be useful, it does have several shortcomings. First, measurements are highly dependent on the skills of the practitioner.