LMFM

There is really no accessible way of knowing what your body fat percentage really is. The measurement methods (say you take weight, height, abdomen, neck, etc) and calculate some formula are easy to do and not too far off. Using calipers to measure skinfolds at 5 or more spots can be more accurate but it depends heavily on the skill of the person doing the measurements. BIA can be more accurate yet, but there are many important factors that can skew the reading: eating, drinking and exercising can affect the results a lot. There are a couple techniques using x-rays. Very accurate but very expensive.

The next best way: hydrostatic weighing. I finally found, here in Denver, a company who does this. But they do not have openings until January.

Until then, you should try this US Navy method. Mine? 4.4 - a few points lower than I want, but a lean, mean, fighting machine!