CPM Calculator

CPM links three numbers, so if you know any two you can find the third:

• CPM = cost ÷ impressions × 1,000. This is what the calculator solves. With the defaults, $500 for 100,000 impressions is a $5.00 CPM.
• Cost = CPM × impressions ÷ 1,000. Say a publisher quotes a $6.50 CPM and you want 250,000 impressions: the buy costs $1,625.
• Impressions = cost ÷ CPM × 1,000. Say your budget is $2,000 and you expect an $8 CPM: you can plan on about 250,000 impressions.

The calculator only solves for CPM, so for the other two either use the formulas above or adjust the cost or impressions field until the CPM matches your quote. One display note: the cost-per-impression line is rounded to the cent, so at a $5 CPM it shows $0.01 even though the exact figure is half a cent ($0.005).

The three metrics divide the same spend by different outcomes:

• CPM: cost per 1,000 impressions. You pay for the ad being shown.
• CPC: cost per click = cost ÷ clicks.
• CPA: cost per acquisition = cost ÷ conversions (a sale, sign-up or whatever you count).

They connect through your click-through rate (CTR) and conversion rate. Say you buy at an $8 CPM, 0.4% of impressions are clicked and 2% of clicks convert. Each click then costs $8 ÷ (1,000 × 0.004) = $2.00, and each conversion costs $2.00 ÷ 0.02 = $100. That chain shows why a CPM price on its own tells you little about what a customer will cost.

Here are two hypothetical campaigns, each run through the same formulas:

Campaign A buys impressions at less than half the price, yet each conversion costs nearly three times as much. Compare on CPM when your goal is reach and the placements are alike in format, audience and how likely the ad is to be seen. When the goal is clicks or sales, compare on CPC or CPA, and use CPM to plan budgets.

Effective CPM (eCPM) turns any pricing model into a per-1,000-impressions figure so you can compare them. A campaign paying $0.80 per click with a 0.5% CTR earns $0.80 × 0.005 × 1,000 = $4.00 per thousand impressions. If another advertiser offers a flat $5 CPM for the same slot, the flat rate pays more unless the CTR rises.

RPM (revenue per mille) measures earnings per 1,000 page views rather than per ad impression. Say a site earns $45 from 30,000 page views: its RPM is $1.50. RPM and eCPM differ because a page can carry several ad slots, and not every page view shows every ad. You can use this calculator for either: enter revenue in the cost field and page views or ad impressions in the impressions field.