Campaign Cost and Budgeting in Facebook

There's no set cost for ads or sponsored stories, and as an advertiser, you can control how much you spend for each campaign by setting a daily or lifetime budget. 

When you run your ad or sponsored story, you will be charged either for the number of clicks (CPC) or impressions (CPM) your ad or sponsored story receives. The amount that you are charged will never exceed your daily or lifetime budget, and there are no additional fees associated with running ads or sponsored stories on Facebook.

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