how do I determine what is the conversion rate of pay per click campaign i am running on facebook?

[Jake Birdem]

The math is relatively simple, but it's more tricky to track individual ads conversion rates. I don't believe Facebook pass any tracking codes to your site, while you can manually compare the Facebook click stats to your sales to get overall conversion, but you may not know if one ad was responsible for more sales even if it had the same number of clicks as the others. (One assumes the ad that generates the most clicks is the best but the can be exceptions)

Adwords campaigns can be setup to pass tracking code tailored for a few of the major affiliate sites, perhaps Amazon, CJ and clickbank (I don't really really recall now) this can help identify whether Adwords was the source when you are running multiple traffic sources.

The only average that comes to mind is the very rough 1% average conversion sales pages that's often cited.