How the heck do you even measure that ish?
the skin calipers are the easiest and most useful for most folks 'normal' needs. truth be told the calipers and biometric impedence devices are pretty much garbage.
1. calipers are going to have built in error based on who is doing it, and how consistent they are.
2 for the biometric impedence deal, i have had those things be as much as 8 or more % off. it's told me when i was super lean in the 7% range that i had 2.5 %, which is to say if true, i'd likely be dead. it's also told me when i was superhydrated and ina mass phase that was morbily obese despite walking around looking pretty jacked and defined.
the calipers for tracking changes might be ok if you have the same person due it each time under the same conditions and using the same spots, so it's not very accurate but it can have decent precision.
the most reliable (and least convenient) method is hydrostatic measurements. you have to use it is the only way to really account for volume and density of tissue differences and hydration status.