Cost Per Mille
The cost an advertiser pays for one thousand ad impressions served, commonly abbreviated as CPM. It is the standard pricing unit for display and video advertising across programmatic and direct buying channels.
Cost per mille (CPM) is the foundational pricing metric in digital advertising. An advertiser paying a $5 CPM spends $5 for every 1,000 times their ad is displayed. CPM pricing is standard for awareness campaigns, display advertising, and video ads where the goal is reach rather than direct response.
For growth teams, CPM is both a cost input and an optimization target. Lower CPMs mean more impressions per dollar, but cheap impressions on low-quality inventory often fail to drive meaningful outcomes. The real skill is optimizing effective CPM, which means finding inventory where the CPM relative to conversion probability produces the best cost-per-acquisition. AI-powered bidding systems excel at this calculation, dynamically adjusting CPM bids based on predicted conversion rates for each impression opportunity. Growth engineers should track CPM trends across channels and segments to identify rising costs early and reallocate budget before efficiency degrades.
Related Terms
Programmatic Advertising
The automated buying and selling of digital ad inventory using software platforms and algorithms, replacing manual negotiation with real-time, data-driven decision-making across display, video, and native channels.
Demand-Side Platform
A software platform that enables advertisers and agencies to purchase digital ad inventory across multiple ad exchanges through a single interface, using data and algorithms to optimize bidding and targeting decisions.
Supply-Side Platform
A technology platform used by publishers and app developers to manage, sell, and optimize their advertising inventory across multiple demand sources, maximizing revenue per impression through automated auction mechanics.
Ad Exchange
A digital marketplace that facilitates the buying and selling of advertising inventory between advertisers and publishers in real time, operating as a neutral auction platform connecting DSPs and SSPs.
Real-Time Bidding
An auction-based mechanism where individual ad impressions are bought and sold in real time as a user loads a page, with the entire bidding process completing in under 100 milliseconds per impression.
Header Bidding
A programmatic technique where publishers simultaneously offer ad inventory to multiple demand sources before calling their primary ad server, increasing competition and revenue by allowing all bidders to compete on equal footing.