After your ad is served more than 500 times, it receives a daily relevance score between 1–10. A score of 10 means we estimate your ad as being highly relevant and a score of 1 means we estimate it’s not very relevant. You can view the score in the Ads Reporting tool by clicking the “Ads” tab.
When your ad is relevant to your audience, its relevance score is higher and is more likely to be shown than other ads targeting the same audience. As a result, you pay less to reach your audience. Use the ad relevance score as an indicator that it’s time to refresh or test your ads.
How Facebook Pricing Works
The more relevant we predict an ad will be to a person, the less it can cost the advertiser to show the ad to that person.
After an ad wins an auction based on its Total Value, the price paid for the winning ad is based on the total value lost by advertisers who competed in the same auction and lost. Because your price is based on the value lost by all of the advertisers you’ve displaced, and not just one bidder, this minimizes the ability for people to “game” the auction by trying to undercut any single bidder.