Cross-platformGoogle AdsMeta AdsLinkedIn Ads2 min read

CPM: definition, formula and use in digital advertising

CPM measures the cost of a thousand impressions. Formula, worked example, what makes it move and what it really tells you about a campaign.

AT
Adwise Team
Editorial ·
Contents
  1. Definition
  2. Formula
  3. Worked example
  4. Orders of magnitude
  5. The most common mistakes
  6. Where to find the metric
Key takeaways
  • CPM is the cost of a thousand impressions, not of a thousand people reached.
  • On Meta it reflects competitive pressure on the targeted audience first, not creative quality.
  • A rising CPM is only a problem if cost per result rises with it.

Definition

CPM, cost per mille, measures what it costs to display an ad a thousand times. An impression is a display, not an attentive view nor a distinct person.

Formula

CPM = total cost divided by number of impressions, multiplied by a thousand.

Worked example

A campaign spends €900 and generates 120,000 impressions. CPM is €7.50. If those impressions reach 30,000 people, each person saw the ad four times on average: that is frequency.

Orders of magnitude

On Meta, observed CPMs commonly run from €5 to €20 depending on country, placement and season, with marked peaks in November and December. On LinkedIn Ads they are appreciably higher, the audience being narrower and more contested. These ranges shift from year to year: treat them as landmarks, not norms.

The most common mistakes

  • Confusing impressions with people reached. A thousand impressions can mean a thousand people seeing it once, or a hundred people seeing it ten times.
  • Judging a creative on its CPM. CPM depends mostly on the audience and on auction competition. Click-through rate tells you far more about the creative.
  • Optimising CPM downwards. Broadening an audience mechanically lowers CPM, often at the expense of the result.

Where to find the metric

In Meta, the CPM column, next to CPP, cost per thousand people reached, which is more useful for judging saturation. In Google Ads, the Avg. CPM column, relevant on Display, YouTube and Demand Gen, not on the Search Network. In LinkedIn Ads, the CPM column.

Frequently asked questions

CPM relates cost to impressions, CPP to people reached. When frequency climbs, CPM can stay flat while CPP jumps: that is the signal of a saturated audience.

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Adwise Team
Editorial

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