Body fat estimate

I am trying to get an estimate of my body fat (I know it's not perfect, but I do want to get the general idea). I've used a number of different calculators and have ranged between 20-30%! Can anyone recommend a method that will give me the most accurate measurement I can get? (I'm thinking about the ones that measure various body circumferences, etc, not skinfold tests or anything fancy-ish.)

These are the measurements that I've had to put in thus far, they might help:

Calf- 9 inches
Thigh- 14 inches
Hips- 36 inches
Navel- 30 inches
Waist- 28.5 inches
Neck- 14 inches
Wrist- 6 inches
Height- 5 feet
Weight- 124

I'd also like a decent calculation method, or an idea of how accurate the impedence methods are. I have a Tanita scale, but I don't know how accurate it actually is.