how accurate are those body fat calculators onlines? the ones that ask for your waist, neck, etc?

I've been checking body fat percentage online since it is convenient and I'm just wondering how accurate the numbers might be.

Public Comments

1. online body fat things are scientific and all, but if you ask me the best body fat calculator is your mile time and how many pushups you can do.
2. correctly accurate
3. fairly correct, u can also ask for a test at your gym, they use calipers for that