body fat

The only truly accurate ways to measure bodyfat are a displacement method - either air (aka bodpod) or water - if you have a university near you with an Exercise Science department you can probably get this done for $50-100, depending on where you live (the university near me charged $50 the last time I had it done)...or a DEXA scan (Dual Energy X-ray Absorptiometry) - which is difficult to find and pretty expensive (like $250+).

The second most accurate method is skinfold testing, with the skin fold measurements being taken by someone who has been trained on how to use the calipers (and preferably to have the same person take the measurements each time). This is probably the most accurate method for the majority of people, because any personal trainer worth their salt at a local gym *should* know how to do skinfold testing.

Bioelectric Impedance methods (BF scales or those handheld devices) are basically the least accurate (outside of the US Navy calc using waist/neck/height for men and hips/neck/height for women). The results can vary significantly, depending on how hydrated you are...and can be off by anywhere from 5-10%! These methods are best used for tracking BF trends, as opposed to actual BF %, provided that you are measuring using the same hydration levels each time (ie you'll know that your BF is decreasing over time, but you won't know your *actual* BF %). Not to mention the fact that BI methods are known to be completely inaccurate for people with very low BF.

HTH!

Dexa or Bod Pod (Although it's hard to find a place where they do them)