What is CPM? Cost per mille explained

CPM (cost per mille) is the cost of 1,000 ad impressions.

How is CPM calculated?

CPM = ad spend ÷ impressions × 1,000

Example

An ad set that spends $330 for 30,000 impressions has a CPM of $11.

Why does CPM matter for e-commerce?

CPM reflects how expensive it is to reach an audience. Rising CPMs with steady click-through usually mean more competition in the auction; rising CPMs with falling engagement often point to creative fatigue.

How does Posta use CPM?

Posta's agents use CPM when reviewing your accounts and recommending changes. See the AI Meta ads management page for how it fits into your workflow.