CPM formulas
CPM = cost ÷ impressions × 1,000
Cost = impressions ÷ 1,000 × CPM
Impressions = cost ÷ CPM × 1,000
Related ad metrics
- CPC = cost ÷ clicks
- CTR = clicks ÷ impressions × 100
- Cost per conversion (CPA) = cost ÷ conversions
- Conversion rate = conversions ÷ clicks × 100
Using CPM to plan a budget
If you want 250,000 impressions and the platform's CPM for your audience is about $8, set a budget of 250,000 ÷ 1,000 × $8 = $2,000. Then watch CTR and cost per conversion: a cheap CPM with poor engagement can cost more per sale than a higher CPM with a better audience.
Measuring returns? Use the ROI calculator or the profit margin calculator.
Last reviewed October 2026.
Frequently asked questions
What does CPM mean?
CPM means cost per mille, or cost per thousand impressions. It is what an advertiser pays (or a publisher earns) for every 1,000 times an ad is shown. "Mille" is Latin for thousand.
How do you calculate CPM?
CPM = total cost ÷ impressions × 1,000. If a campaign costs $500 and gets 100,000 impressions, the CPM is $500 ÷ 100,000 × 1,000 = $5.00.
What is a good CPM?
It depends on the platform, audience and season. Broad display ads can cost $1 to $5 CPM, social media ads often $5 to $15, and highly targeted B2B or video audiences $20 or more. Lower is cheaper reach, but what matters most is cost per result.
What is the difference between CPM, CPC and CTR?
CPM is the cost per 1,000 impressions. CPC is cost per click: total cost ÷ clicks. CTR (click-through rate) is clicks ÷ impressions × 100. They are linked: CPC = CPM ÷ (CTR × 10).
What is RPM for publishers and YouTubers?
RPM (revenue per mille) is what a publisher or creator earns per 1,000 views or page views after the platform's share. It is usually lower than the advertiser's CPM. You can use this calculator with RPM and earnings the same way.