I'm trying to figure this out. My understanding is that bf% calculations give you your bf% based off volume, not mass. Is that correct? That is to say, if you weight 200lbs and had 25% bf, it would be innacurate to say that you had 150lbs of lean mass because of the different densities of fat versus muscle.

I did some googling and found that muscle was ~18% denser than fat, or 1.06g/mL vs .9g/mL.

I lost ~13lbs and 2.1%bf according to a handheld bioimpedance bf calculator (which I can be horribly inconsistent). So what I'm trying to figure out is if I weighed 202 to begin with, lost 2.1%bf, how many pounds of fat should I have lost.

Does anyone have a formula for this already figured out? Or am I wrong on some of my assumptions?

Thanks

Someone suggested the Army's formula for BF%. The tanita scale was telling me 16% which seemed high. The Army's formula pegged me at 13% which I think is more accurate. It's based on age, height, neck circumference, and waist circumference.

http://www.calculator.net/army-body-fat-calculator.html

I'm pretty sure that it's a percent by mass, not volume.

The Army's BF calculator is the most inaccurate ever imagined. If you have a fat stomach and a fat neck, you are fat.

I'll second what Rangers said... the Army's BF scale is ridiculous. It says a guy my height, 5'7'', should weigh 169 lbs.

Craziness. I'm 20 lbs. over that and am definitely one of the most fit people in my company.

We used the Army's BF calculator in the Corps, and there were certain people that had no business passing that passed because they had absurdly fat necks. But I think if you have a "normal" neck, it shouldn't be too bad.