CPM (Cost Per Mille)

Cost per mille (CPM) is the price paid per thousand ad impressions. It is the native currency of programmatic auctions: bids are expressed as CPMs even when the advertiser's goal is installs or purchases.

CPM buying suits reach-oriented goals such as CTV campaigns, brand awareness and creative testing at scale, where the advertiser wants control over where and how often ads appear. For performance goals, the DSP translates a target CPI, CPA or ROAS into a CPM bid for each impression based on the predicted chance of conversion. A high CPM is not necessarily bad: premium placements can cost more per thousand yet deliver cheaper installs because they convert better.

When comparing partners, look beyond the average CPM to how it varies by placement, format and hour; those patterns often reveal where the efficient inventory actually sits. A partner that cannot show this breakdown is asking you to trust a blended number.