CPM

CPM is both a billing model and a reporting metric. As a billing model, you pay each time your ad is shown, priced per thousand showings, whether or not anyone clicks. As a metric, it is spend divided by impressions, multiplied by 1,000, which lets you compare the cost of attention across channels billed in different ways.

In ChatGPT ads, the Views objective is billed on CPM, and eligible advertisers on the Conversions objective can choose oCPM, which optimizes toward conversions while billing impressions. Gravity bills CPM across its Clicks, Reach and Conversions objectives: even a campaign optimizing for clicks pays per 1,000 impressions.

Both channels report CPM. It appears in ChatGPT’s reporting metrics and in Gravity’s ad-unit reports alongside impressions, clicks, spend, CTR and CPC.

CPM buys exposure, so pair it with an outcome metric before judging a channel: a low CPM with a weak click-through rate can cost more per visitor than a higher CPM with strong engagement. When comparing channels, convert each to the same unit, such as cost per click or cost per conversion, rather than comparing a CPM on one channel with a CPC on another. In Admux, your charge is the provider’s media cost multiplied by one plus the channel’s disclosed markup, so your effective CPM through Admux is the channel’s CPM plus that markup. GET /channels shows the current markup for each channel.