A lot of equipment is needed, usually found at most Universities. Time consuming and sort of a hassle. What you eat the day before, or before the test, can affect the accuracy. Thought to be very reliable. The more places tested the more accurate the results.
Most gyms have a caliper.
If the person is inexperienced the results may be very inaccurate. Men generally store FAT around their waist, while women generally keep it around their hips. The best way to get and keep a washboard stomach, or shapely hips, is by following a low FAT diet and doing plenty of aerobics. Crunches, or side leg raises, while strengthening and building the muscles, will not make them appear through the layer of FAT between them and the skin. This is usually taken by pressing on the front, left side of the neck, or the inner wrist, and counting the number of beats in a certain time.