CPM (cost per mille)

CPM prices one thousand impressions — cost divided by impressions, times 1,000 — and the bar for counting one is lower than most buyers assume. Under the IAB/MRC definition an impression is credited once the ad has been successfully delivered to the device and has begun to render, which does not necessarily mean it was seen. In the Amazon stack CPM is the currency for Amazon DSP, where line items carry base and max supply bids quoted as CPMs and Amazon Ads also supports pre-negotiated fixed-CPM campaigns; for audio ads; and for streaming TV ads bought through sponsored ads, billed on CPM with no minimum budget required. The exception is Sponsored Display, whose only two cost types are cpc and vcpm — the viewable variant. Sponsored Products and Sponsored Brands stay CPC.

CPM is a quoted rate, not a paid rate, and on Amazon the gap runs two ways. On DSP the bid covers media cost only: Amazon's pricing transparency guide describes a percent-of-media-cost tech fee, a percent-based managed-service fee, and Amazon audiences, third-party audiences and pre-bid targeting each invoiced at their own published CPM — so rebuild effective CPM from invoiced cost over delivered impressions, never from the bid. On Sponsored Display the trap is the denominator: you pay per viewable impression while the Impressions column counts served ones. Read the vCPM column instead, and take viewable over served as your viewability rate. Third-party verification vendors are integrated on the Amazon DSP side, so treat onsite vCPM as seller-measured and push volume that has to be verified into DSP.