Here’s two time points with the various formulas and compared with various “direct measurement” techniques. Decent agreement and I like the tight SD (and I like bracketing what the formulas give). The formula labeled Dave Draper is “modified YMCA” formula. When you get that low BF it’s all how you look anyway. Obviously your mileage may vary given your metrics.
Here’s the formulas for you obsessive folks:
Cell D16 is the mean BF from all the formula results (cells D10:D14).
Hope all this detail gives someone who’s really interested an assist. But at the end of the day the waist-to-height ratio is such a simple shortcut.