CPM (cost per thousand impressions)

CPM is the cost of showing an ad one thousand times. It says what reach costs, not whether the reach did anything useful.

Stock photos and example labels, not customers.

Definition

CPM is the cost of showing an ad one thousand times. It says what reach costs, not whether the reach did anything useful.

FormulaCPM = ad spend / impressions x 1,000

Example with made-up numbers: An ad set spends 300 and gets 40,000 impressions. CPM = 300 / 40,000 x 1,000 = 7.50.

How to use it

CPM moves with the audience, the placement, the season and the competition in the auction. A rising CPM with a steady click through rate usually means reach got more expensive, not that the ad got worse.

Read it next to click through rate and cost per result. A cheap CPM on an audience that never buys is not cheap.

Related terms

CTR CPC Ad frequency

Go deeper

Measurement

Daily, weekly, monthly: what to look at when

Most bad ad decisions are reactions to a number that is only noise at that time scale. Match the number to the cadence.

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