Google will use generative AI to resize your Performance Max videos unless you opt out
Advertisers have until September 4 to disable automatic AI-driven video reformatting inside Performance Max campaigns.
Mariano De Vitto · September 2026
Google Ads is preparing to hand its generative AI systems another piece of creative control, this time over the actual shape of your video ads. According to a report from Search Engine Land, Google will begin using generative AI to automatically resize existing video assets in Performance Max campaigns into new aspect ratios, and advertisers who want to keep things as they are have until September 4 to opt out.
The stated goal is straightforward: help a single uploaded video fill more placements across YouTube, Discover and Display by reshaping it into formats it was never originally shot for, without requiring marketers to produce new creative for every surface. Performance Max, Google's automated campaign type that spans Search, Display, YouTube, Discover, Gmail and Maps from one unified setup, has always leaned on advertisers supplying a pool of assets that Google's algorithms then mix and match. Generative video resizing pushes that automation one step further, letting Google fabricate the missing formats itself rather than waiting for a vertical or square version to be uploaded.
How the opt out works
Per the report, this generative expansion will apply by default across Performance Max campaigns that include video assets. That means brands that take no action will simply see their existing footage reformatted by AI into vertical, square or other aspect ratios automatically, with no additional approval step. Advertisers who want to keep tighter control over how their video creative appears, whether for brand safety reasons, concerns about AI-altered framing, or worries about scenes being artificially extended to fit a new ratio, need to actively find and use the opt out setting inside Google Ads before the September 4 deadline. There is no indication in the report of a grace period or a way to reverse the setting retroactively once campaigns have started running with the new formats.
Automation stacking on automation
This is not an isolated move. It fits a broader pattern of Google embedding generative AI deeper into Performance Max, a campaign type that already asks advertisers to hand over significant control of creative assembly and bidding strategy to its algorithms. For marketing teams, that means generative resizing does not arrive as a standalone feature, it arrives as another layer stacked on top of automated bidding, automated asset combination testing and now automated reformatting of the footage itself. Each layer individually promises efficiency and scale, but together they compound the distance between what a brand team designs and what ultimately reaches a consumer's screen.
That compounding effect is exactly why brand and legal teams tend to get nervous about defaults like this one. A video shot and approved for a 16:9 YouTube placement was framed, lit and paced with that format in mind. Letting a generative model reinterpret it for a 9:16 Discover feed or a square Display unit introduces creative decisions, what to crop, what to extend, what to leave out, that no human on the brand side has reviewed. For categories with strict compliance requirements, or for brands that have invested heavily in a specific visual identity, that is a meaningful shift in who controls the final ad experience.
What marketers should do now
Why it matters is simple: teams running Performance Max campaigns with video assets have a concrete decision to make this week, not next quarter. Marketing leads who care about maintaining creative control, consistent brand framing, or simply avoiding AI-generated alterations to their video ads without sign off should review their Performance Max settings now and locate the opt out option before September 4. Waiting past that date means defaulting into automatic resizing that was never explicitly approved, and once footage has already been reshaped and served across YouTube, Discover and Display, undoing that exposure is far harder than preventing it in the first place.
The Signal Brief · Mariano De Vitto — Head of Marketing, Barcelona