Online Body fat calculators vs reality

ForecasterJason

For those that have gotten actual accurate testings for body fat, do you know of any online calculators that are very close? I did see this calculator claims to be very close to a water displacement test. I played around with some of the measurements, and it seems like it primarily takes into account height and waist size at the navel though.

yirara

I get 21.69% compared to 29.87 from BMI and age
While I think this is closer to truth I do have a couple of problems with this calculator: what is the equation used? And how do I measure exactly? Do I keep my arm straight when measuring my biceps? What is the widest part of the hips exactly: I've seen measurement examples that are rather at the wides part of both legs together (not uncomon with women), or wides part of the pelvis, which strictly speaking isn't hips either. Oh, and I cannot enter decimals when chosing metric. If that's also the case in inches, then this is a very unprecise calculator indeed!