I personally use Calipers for this reason…
From the research I had to do in college the Bioelectrical Impedance is +/- 12% of the SD (Standard Deviation), basic calipers are +/- 4% of the SD, and hydrostatic weighing is the “gold standard”. It’s not realistic to have our clients get into their swimsuits to take their BF% nor is convenient or economical, so hydrostatic weighing is out of the questions. So when it comes to better SD, which means more accuracy, I choose calipers. I suggest using calipers as long as you’r consistent and accurate with your pinches for each client. Also, the more sites you take with the calipers the better the reading.
I don’t use the BIA because it uses an elecrical current to measure BF% and there are too many factors that come into play such as: temperature of the room and fluid intake. You’re going to have a better BF% reading in warmer/hotter temperatures than a colder room due to more blood/liquid flow in the body and less constriction. If your client drinks more water, then he/she will have a better reading because water conducts the electrical current better which means a fast/better reading, where it’s the opposite if your client didn’t drink much fluids.
I still have my college scientific paper on “Body Composition Assessment” if anyone’s interested.