I didn't find the site I got measurements from, but I did find this site with several different ways to calculate your body fat. I think one of them is the one I used to use.
I love these measurements, because they say I am making much more progress than my scale says. According to them, I'm “only” 35 pounds of fat, instead of 45 pounds of fat, which is what my scale has been saying the last couple of weeks. (Yes, I know a lot of people out there are grossing out over 35 pounds of fat, but I do have large breasts carrying some of that.)
I've been going down in weight on the scale, but it's been from muscle and since I'm following my diet, I don't know what the problem is other than that the scale is wacky. I did replace the batteries on the scale today, in the hopes that they had something to do with it.