CPC

Under CPC billing you pay only when someone clicks, which makes it a common model for placements driven by intent. As a metric, CPC tells you what each visit costs regardless of how the channel bills.

Google’s AI placements use the same auction as Search, with CPC or conversion-based bidding and no extra charge for ads that serve in AI Overviews or AI Mode. In ChatGPT ads, the Clicks objective is billed on CPC; the price comes from an auction in which the final winning bid sets what you pay. OpenAI recommends starting with a maximum CPC of $3 to $5 USD, which is a recommendation, not a reported average price.

Gravity is the exception: it does not offer click billing for new campaigns and accepts CPC only on older ones. Its Clicks objective optimizes for clicks but bills per 1,000 impressions. Gravity still reports CPC in ad-unit reports, so you can compare it as a metric.

Set a CPC target from what a visit is worth to you, which is your conversion rate multiplied by the value of a conversion, and bid below it. On ChatGPT, treat the recommended starting bid as an opening position and adjust from reported CPC and conversion data. On Gravity, calculate effective CPC from spend and clicks, since the bill is in impressions. Through Admux, every channel charge is the media cost multiplied by one plus the disclosed markup, so add the markup when you compare Admux CPC with a figure from a channel’s own dashboard.