What is CPM (cost per mille)?
How is CPM calculated?
Divide what you spent by the number of impressions. Multiply by one thousand.
An impression counts a showing of the ad. It does not count people. The same person can add many impressions.
CPM is the usual price when you buy reach or visibility rather than clicks, as in display and social ads. In search, you more often pay per click, so cost per click is the number to watch.
Is a low CPM good?
Not by itself. CPM tells you what attention cost. It does not tell you what attention was worth.
A low CPM can mean cheap, poor-fit attention. A high CPM can mean a good audience that buys. You only learn which by following the money further down. What did each new customer cost? That is CPA, cost per acquisition. And what did the next euro return? That is marginal ROAS.
For ZFD: We do not judge a campaign by CPM alone. We follow it through to what the orders left after costs. See paid media strategy for ecommerce for how we pick channels by margin.
Worked example
Easily confused with
CPM vs CPC
You pay per click, not per thousand showings.
CPM vs CPA
Spend divided by the conversions the platform counts.
CPM vs Cost per million
A common slip. The M stands for mille, so it is per thousand.
CPM vs Impressions
The count that CPM divides by.
FAQ
Does M mean million?
No. M stands for mille, Latin for thousand. CPM is the cost per thousand impressions.
Why does CPM change?
Many things can move it, so a higher CPM alone does not say your campaign got worse. Ask what changed alongside it.
Is CPM the same as cost per result?
No. CPM prices showings. A result needs someone to act. The gap between them is where the money is won or lost.
Sources
Let’s find what’s actually working.
Next step. Check what your ad numbers look like on explicit assumptions. Use the Is your ROAS real? calculator.