Durnin Wormersley and Jackson Pollock. The skinfold calipers I use do the calculation for you. They are called Skyndex. They are pricey but effective. It uses the Jackson Pollock formula.
Joanne is right skinfold calipers should be pretty accurate with the four spot measurement or 3 spot measurement for clients with lower body fat. Decent calipers are $15 to $200+ and usually come with a chart for the measurements or an alternative is electric impedance measurement with a specially designed body fat measuring scale. I use the cheap slimline calipers but I’d like to get one that is smaller and more comfortable
In my opinion, the best method is still hydrostatic weighing because it is safer than a DEXA (Dual-energy X-ray absorption) scan, but both hydrostatic weighing the DEXA scan are fairly comparable to each other as far as providing the closest estimate of true body fat. There is also something called the Bod Pod. This device is a chamber that you get into that measures the overall air displacement of your body. I don’t know how it works exactly, but it’s supposed to be able to better account for hydration, the volume of air in your lungs, and other extraneous factors that often affect body fat analysis. Any of the above three techniques would yield the best results when measuring body fat. It’s not often that you see fitness centers with these facilities, however. Even then, you would need some certified medical professionals to conduct the tests and give clients directions on how to control for certain factors (like hydration).
For fitness professionals today, the two best methods out there in my opinion are skinfold calipers and Bioelectrical Impedence Analysis (BIA). I tend to err on the side of BIA because it’s more comfortable for the client. Even though it’s not as accurate as I would like it to be, I think it gives an accurate representation of body fat changes over time. This method can vary up to 5 percent give or take. It’s all dependent on how much water is in the body, ultimately. It’s hard to control for that. For women, the menstrual cycle can affect this measurement.
Skinfold calipers are great if you know what you’re doing. The problem is that a lot of people don’t use them correctly, and you might as well be throwing darts at a dart board. I, personally, find it very difficult to separate the fatty layers from the muscle underneath when pinching. Not only that, I’m always worried about my fingers slipping and pinching the client, which isn’t good for our relationship when I’m doing the initial assessment. So, call me inept, but I prefer BIA. Yes, there is a wide range of variability, however I view it as having less variability than if I were to inaccurately separate the fatty layer from the muscle underneath. I also see it as less invasive for the client. The BIA can be done quickly. This means that we can take measurements over a week (in a perfect world, at the same time of day) and average those measurements to get a more accurate assessment of body fat. That’s if we’re really interested in body fat. My experience is that body fat is less of a concern than are body image, strength, and functional movement. As long as body fat falls within an acceptable range for health give or take 5 percent, I think body fat shouldn’t be the focus of a training program.
nothing is going to be absolutely accurate and with any calipers (and I like the Skyndex that was mentioned) it is dependent on your experience and consistency doing it. DEXA is good because you can get bone density as well, Hydrostatic weighing has been and still is the gold standart, bodpod is pretty accurate but might be hard to find one.
Nothing wrong with a tape measure and watching the inches get smaller. I have learned through experience that body fat % is less important that losing inches and for obese clients can be a negative experience.
Hydrostatic weighing is the standard (didn’t know about DEXA, thanks for that one) but I’ve only seen it used in the clinical setting. I have used calipers since 2002 and have very good consistency now but that took time. If your really looking to dial in the results you may have to go with more elaborate (hydrostatic and DEXA) methods. Its not cheap so be sure its necessary. Personally, 7 site calculations have given me the most consistent results and it also allows a good image of the clients body fat distribution. I use this distribution to assist in obese related cases, to detail possible underlying issues.