CPM (cost per mille) is the price an advertiser pays for 1,000 ad impressions. The formula is (Total Cost ÷ Impressions) × 1,000 — spend $500 for 200,000 impressions and the CPM is $2.50. This calculator works in three directions: enter cost and impressions to find CPM, enter CPM and impressions to find cost, or enter cost and CPM to find how many impressions the budget buys.
CPM vs. CPC vs. CPA
CPM charges per impression regardless of clicks. CPC (cost per click) charges only when someone clicks. CPA (cost per acquisition) charges when a user completes a conversion. CPM suits brand awareness campaigns where the goal is visibility. CPC and CPA suit performance campaigns where the goal is action. Comparing CPM across channels reveals which platform delivers the cheapest exposure for the same audience.
What Counts as a Good CPM
CPM varies by platform, audience, and format. Social media display ads often run $5–$15. Programmatic video can reach $20–$40. Connected TV averages $25–$45. A lower CPM is not always better — a $30 CPM that reaches in-market buyers may outperform a $3 CPM on a low-quality network. Evaluate CPM together with click-through rate and conversion rate to judge actual efficiency.
Using CPM for Budget Planning
Switch to the cost mode to answer 'how much will 1 million impressions cost at $8 CPM?' — the answer is $8,000. Switch to the impressions mode to answer 'how many impressions can $5,000 buy at $12 CPM?' — about 416,667. These back-of-envelope calculations help set campaign budgets before committing spend in the ad platform.
CPM in Programmatic and RTB
In real-time bidding, the CPM you set is a bid ceiling. Actual CPM depends on competition, audience segment, and ad quality score. Winning bids are often below the max — a $10 CPM bid might clear at $6.40. Monitor effective CPM (eCPM) in campaign reports to see what you actually paid per thousand.
FAQ
Q: What does CPM stand for?
A: CPM stands for 'cost per mille.' Mille is Latin for thousand. A $10 CPM means $10 per 1,000 impressions.
Q: Is a lower CPM always better?
A: Not necessarily. Cheap impressions on low-quality inventory may generate no engagement. Compare CPM alongside click-through rate and conversion metrics to judge real value.
Q: How do I convert CPM to cost per impression?
A: Divide CPM by 1,000. A $10 CPM equals $0.01 per impression.