Do you sometimes wonder how they calculate the number of stars a listing has earned? Maybe you're looking at a listing that's got a lot of crummy ratings, but seems to have a lot of stars. Or maybe it's a listing that looks like it's got good ratings lately, but it has less than 5 stars. Or maybe you've got a listing that's had some bad ratings and you'd like to find out how many good ratings it's going to take to pull it up.

Take, for example, the listing on the left. It's not at all clear to look at it how it earned those stars, or whether it deserves them.

It's just a matter of averages, but it's a little obscure how they figure it. What they do is multiply the five star ratings times 5, the four star ratings times 4, the three star ratings times three, the two star ratings times two, and the one star ratings they leave unchanged. then they add up the points and divide by the number of ratings given.

I've made a ratings point calculator for figuring this out. Just enter the number of ratings for the different numbers of stars to find out the numeric point value of the ratings, so you can see why it's where it is.

Now this won't work for an old listing that had ratings before the cutoff date. We've lost that information forever. But it should work for any listing newer than that.