What Is CPM? — Free Tool
CPM is the cost of a thousand impressions. The formula, why the M means thousand, what moves CPM up and down, and why a cheap CPM is not automatically a good buy.
Cost per mille: what you pay for a thousand impressions. It is the standard way to compare the cost of attention across platforms and campaigns.
What it is
CPM is what you pay for a thousand impressions. It is the standard unit for pricing attention, and it lets you compare the cost of putting a message in front of people across platforms, placements and time.
How it is measured
Total spend divided by impressions, times 1000. Six hundred spent for 250,000 impressions is a CPM of 2.40. The M is the Roman numeral for a thousand, from mille, so despite appearances it never means million.
Commonly misunderstood
The most common error is treating a low CPM as a win. CPM prices attention but says nothing about whose attention. Broad, cheap audiences on low-value placements such as Audience Network can deliver a CPM a fraction of feed placement while converting far worse, so CPM should always be read next to CPC and cost per conversion. The second error is comparing CPMs across markets and seasons: an auction is a market, so the same audience costs more in Q4, and B2B targeting on LinkedIn is structurally many times the price of broad consumer targeting on Meta. The third is applying CPM to organic reach, which was never bought and therefore has no price.
When it matters
Use CPM to judge whether media is getting more or less expensive over time, and to sanity check a platform's efficiency before you look at creative. A rising CPM at flat performance means auction pressure, not a content problem.
Related terms
Features
- The CPM formula written out, with a worked example
- Why the M stands for mille and not million
- What pushes CPM up: audience size, seasonality, placement and competition
- Why the cheapest CPM often buys the least valuable attention
- A linked calculator that works out CPM, CPC and total spend together
Frequently asked questions
What is the CPM formula?
Total spend divided by impressions, times 1000. Spending 600 for 250,000 impressions is 600 / 250000 x 1000 = 2.40, so a CPM of 2.40.
Does the M mean million?
No. It is the Roman numeral for a thousand, from the Latin mille. CPM is cost per thousand impressions, which is why the formula multiplies by 1000.
What is a normal CPM?
It varies enormously by market and audience. Broad consumer targeting on Meta often sits in the low single digits, while narrow B2B targeting on LinkedIn regularly runs above 30. Compare CPM only against your own history in the same market and season.
Why did my CPM jump in November?
Seasonal auction pressure. Q4 retail demand raises what everyone bids, so the same audience costs more from roughly Black Friday through late December on Meta and Google.
Does organic content have a CPM?
Not really. CPM is a price and organic impressions are not bought. Some teams compute an earned media value by multiplying organic impressions by a notional CPM, which is a rhetorical device rather than a measurement.
