Advertising
CPM Calculator
Cost per thousand impressions, solved from whichever two numbers you have.
The formula
CPM is cost per thousand impressions — the M is the Roman numeral, not "million". Spend ÷ impressions × 1,000. A $1,000 campaign that served 200,000 impressions ran at a $5 CPM.
CPM is a price, not a result
A low CPM only means impressions were cheap. Cheap impressions shown to the wrong people cost more per customer than expensive impressions shown to the right ones, which is why CPM is worth watching but never worth optimising on its own.
The numbers that decide whether a campaign works sit further down the chain: cost per click, cost per conversion, and whether your ROAS clears 1 ÷ margin.
What moves it
Audience size and overlap, competition in the auction, seasonality, placement and creative quality all move CPM. Q4 in most consumer categories is the clearest example — the same audience costs materially more in November than in February.