CPM equals cost divided by impressions, multiplied by 1,000. A $5,000 campaign that served 400,000 impressions has a $12.50 CPM. To go the other way, impressions equal spend divided by CPM times 1,000, and spend equals impressions divided by 1,000 times CPM.
What moves it
Use effective CPM to compare buys priced on clicks, views, or flat fees: divide the total cost by the impressions actually delivered. Compare CPMs only within a channel and format, since a $3 display CPM and a $30 CTV CPM buy different things.
Run your own numbers with the CPM calculator.
Cite this page:
Agency Echelon. "How do you calculate CPM?" Agency Echelon Reference, reviewed September 2026. https://agencyechelon.com/reference/questions/how-to-calculate-cpm/