ChatGPT Ads 将用 Target CPA 和 Target CPC 替代 Max Bid 与 Max CPC

The ChatGPT Ads platform is replacing two manual caps, the maximum bid (Max Bid) and maximum CPC (Max CPC), with average cost targets that advertisers can set as part of their advertising campaign strategy. This is according to an OpenAI help document on the topic of bidding and pricing that was updated on their website Thursday.

Beginning Nov. 9, advertisers creating a conversion campaign, which they are using to hit a specific cost per conversion, get Target CPA in place of Max Bid; likewise, advertisers creating a click campaign beginning Nov. 9 also have the option to use Target CPC. Max Bid and Max CPC will no longer apply to existing campaigns from Jan. 1, 2027.

From Nov. 18, a Max Bid or Max CPC value that an API partner sends through the old fields to create a campaign or change an ad group’s bid type becomes an average target, not a maximum.

What Target CPA And Target CPC Change

OpenAI’s bidding page describes Target CPA and Target CPC as average cost goals rather than limits on each bid. Target CPA is the average of what an advertiser wants to spend on a conversion (such as a purchase or a lead) and Target CPC is the average for a click. In both cases, a single click or conversion may cost more or less than your target, and you may end up paying more or less on average.

For click campaigns, the page compares the new option with the cap it replaces:

“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 warning on this page is about a possible restriction on delivery when the target is set below recent performance. An example shows how they calculate a $40 actual CPA using $400 in ad spend and 10 attributed purchases. It points out that if a $20 Target CPA is set it does not mean that the system will be able to deliver purchases at a $20 cost. Additionally, the amount spent by a campaign may fall short of the full budget due to overly restrictive targets or poor conversion data.

This page says the bidding goal and the billing event type are two different settings and therefore, a Target CPA campaign can be optimized for conversions while being charged for clicks or impressions, which depends on how the campaign is being billed.

In August Brooke Osmundson reported that Microsoft would cease to offer Max CPC on new non-portfolio campaigns using a strategy such as Target CPA and Target ROAS beginning Oct. 1. However, existing campaigns and portfolio bid strategies may continue to use it. Microsoft’s official reasoning behind the change is that the setting can interfere with their bidding systems’ ability to perform optimizations toward performance objectives.

API Bid Fields Change On Nov. 18

API partners are getting their own Target CPA and Target CPC fields, and the old Max Bid and Max CPC fields change behavior on Nov. 18. The bidding page says partners can adopt the new fields once they’re available but doesn’t give a date for them.

OpenAI suggests that the legacy fields be replaced with the new fields starting Nov. 18. Legacy fields will stay active until the end of December; however, if you utilize a field to create a campaign or convert an ad group’s bidding strategy, it switches to Target CPA or Target CPC and the value becomes counted as an average cost instead of a maximum bid.

On Jan. 1, 2027, legacy fields will be deprecated. As such, the page advises partners to have all integrations updated prior to this date.

What OpenAI Says You Pay

OpenAI’s bidding page also explains how the price of a winning ad is set:

“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 page says.

The company’s advertiser basics page described a relevance-weighted, second-price auction when I read it on Nov. 5. However, that wording is gone after an update, and the page now uses the same pricing rule as the bidding page.

The basics page also still says advertisers set a maximum bid at the ad-group level, and it recommends that CPC campaigns start with a maximum bid of $3 to $5 per click. In April, I covered Digiday’s report that an early version of the ads manager showed CPC bids in that range to some pilot advertisers.

The Maximize results page is still telling advertisers who are required to operate within a bid limit that if they have to do so without an automated process, they can do it using manual or advanced bid controls. Its setup steps say to select Manual: Max bid to use a different strategy. Also, the bidding page gives the old Maximize results strategy a new name, Intelligent bidding.

Why This Matters

With Max Bid and Max CPC, advertisers have the ability to limit how much they will bid in each auction. With Target CPA and Target CPC, it is the advertiser who sets both a budget and an average cost; then it is up to the automated bidding systems to set individual bids. Some individual clicks or conversions could come in at higher costs than the targets.

As OpenAI suggests, advertisers should consider setting their targets based upon recent actual CPA or CPC averages. In addition to reviewing the overall spend of the campaign as well as results (clicks, conversions), advertisers should also monitor the actual average cost per click or conversion as the campaign continues to learn. Advertisers who buy through API partners should find out which bid fields those tools use after Nov. 18, since a legacy max-bid value sent to create a campaign will count as an average target.

Looking Ahead

Target CPA and Target CPC are available in Ads Manager beginning Nov. 9, with advertisers able to move their campaigns from this date forward. The legacy API bid field changes behavior on Nov. 18 and is going away Jan. 1, 2027, which marks the end of Max Bid and Max CPC for those who have yet to switch.

There is no information on OpenAI’s bidding page as to what will be the target of a campaign that is still using Max Bid or Max CPC after the caps retire. By switching prior to retirement, the advertiser is able to set its new target at the time of the switch.

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