ChatGPT Ads Drops Max Bid and Max CPC for Cost Targets

OpenAI will stop supporting Max Bid and Max CPC in ChatGPT Ads on Jan. 1, 2027, and from Nov. 9 advertisers can set Target CPA and Target CPC instead, according to a help document updated Thursday. The change removes per-auction bid ceilings and replaces them with average cost goals that the platform's automated bidding systems control.

The rollout has three dates. From Nov. 9, advertisers creating conversion campaigns get Target CPA in place of Max Bid, and click campaigns gain a Target CPC option. From Nov. 18, any Max Bid or Max CPC value an API partner sends through legacy fields to create a campaign or change an ad group's bid type becomes an average target, not a maximum. On Jan. 1, 2027, legacy API fields are deprecated and Max Bid and Max CPC no longer apply to existing campaigns.

What do the new targets change?

OpenAI's bidding page describes Target CPA and Target CPC as average cost goals, not limits on each bid. A single click or conversion may cost more or less than the target, and the average may also land above or below it.

For click campaigns, the page explains the difference directly: "While Max CPC caps individual bids, Target CPC lets our system bid above or below your target in individual auctions, aiming to deliver as many clicks as possible from your budget while working toward your desired average CPC."

The page warns that delivery may suffer when a target sits below recent performance. Its worked example calculates a $40 actual CPA from $400 in ad spend and 10 attributed purchases, then notes that setting a $20 Target CPA does not mean the system can deliver purchases at $20. Overly restrictive targets or weak conversion data can also leave a campaign spending less than its full budget.

One nuance matters for billing. The bidding goal and the billing event type are separate settings, so a Target CPA campaign can optimize for conversions while charging for clicks or impressions, depending on how the campaign is billed.

How should API partners respond?

API partners receive their own Target CPA and Target CPC fields, though OpenAI has not given a date for their availability. The company suggests replacing legacy fields with the new fields from Nov. 18. Legacy fields stay active until the end of December, but any value used to create a campaign or convert an ad group's bid type switches to Target CPA or Target CPC and counts as an average cost.

OpenAI advises partners to update all integrations before the Jan. 1, 2027 deprecation. Buyers using third-party tools should confirm which bid fields those tools send after Nov. 18, because a legacy max-bid value will silently become an average target.

What does OpenAI say about pricing?

The bidding page states the auction rule plainly: "The final winning auction bid sets the price you pay." That rule applies across all bidding strategies, including existing Max Bid and Max CPC campaigns.

The advertiser basics page previously described a relevance-weighted, second-price auction when read on Nov. 5, but an update removed that wording and the page now uses the same pricing rule as the bidding page. The basics page still says advertisers set a maximum bid at the ad-group level and recommends CPC campaigns start with a maximum bid of $3 to $5 per click — a range Digiday reported in April as visible to some pilot advertisers in an early ads manager.

OpenAI has also renamed the old Maximize results strategy to Intelligent bidding. The Maximize results page still tells advertisers required to operate within a bid limit that manual or advanced bid controls are the option without an automated process.

Why the shift mirrors Microsoft

The direction matches a broader platform trend. In August, Brooke Osmundson reported that Microsoft would stop offering Max CPC on new non-portfolio campaigns using strategies such as Target CPA and Target ROAS from Oct. 1, while existing campaigns and portfolio bid strategies keep it. Microsoft's stated reasoning: the setting can interfere with bidding systems' optimization toward performance objectives.

OpenAI recommends advertisers set targets based on recent actual CPA or CPC averages, then monitor spend, clicks, conversions and actual average cost as campaigns learn. The bidding page gives no information on what happens to campaigns still running Max Bid or Max CPC after the caps retire, so advertisers who switch early can choose their own targets rather than inherit an automated conversion.