Key takeaways
- PMax video resizing gives Google more control over how your existing video assets are adapted for vertical and square inventory.
- The main commercial risk is not ugly creative, it is spend shifting towards generated formats that satisfy bidding signals without improving profit or lead quality.
- UK advertisers should create a ratio approval grid, separate asset groups by commercial role, and record generated previews with sign-off notes.
- Performance Max ROAS needs extra scrutiny because brand, Shopping overlap and weak conversion value can reward the wrong creative assets.
- Regulated sectors need compliance checks on resized videos before spend scales, especially where claims, disclaimers or product framing matter.
PMax video resizing is not just a creative convenience. It changes who controls the final version of your advert before it appears across Google inventory. For UK advertisers, that means creative QA now belongs inside PPC management, not just inside the brand team.
Google is taking another step from automated buying into automated production. That matters because Performance Max already decides where budget goes, which asset combinations run, and which users see them. If your team has already been working through Google AI tools for PPC teams, treat this as the creative version of the same pattern: fewer manual checks by default, more responsibility on advertisers to set guardrails.
The advertisers most exposed are not the ones with no video. They are the ones with decent horizontal video, strict brand rules, product-detail shots, regulated claims, or creative that only works when framed exactly as intended.
What’s actually changed in PMax video resizing
Google Ads is rolling out an asset optimisation upgrade for existing Performance Max video ads. The system uses generative AI to extend videos into missing aspect ratios, including versions that fit vertical and square placements.
This builds on existing video enhancements, where Google already adapts horizontal videos into other formats. The new layer is more active. Instead of only cropping or reformatting, Google fills missing creative space so an advert becomes eligible for more inventory.
Advertisers that do not want the generative AI optimisation applied need to use the available opt-out route or change video settings inside Google Ads. The practical point is simple: if you do nothing, Google gains more freedom to adapt your video assets for Performance Max delivery.
Why this matters for advertisers
PMax video resizing moves money by increasing eligible inventory. If Google can turn one horizontal video into more usable ratios, that asset competes in more placements. The system then has more opportunities to spend. That sounds positive until the generated version underperforms, weakens the brand, or attracts cheaper but less valuable attention.
Here is the mechanism. Performance Max does not optimise video quality in isolation. It optimises towards the conversion signals you give it. If an AI-extended vertical video drives lots of low-intent clicks or view-through assisted conversions, the campaign reads that as progress. Budget follows the asset combination. Spend moves away from stronger creative formats and towards the version that appears to satisfy the bidding model.
That is where reported ROAS gets dangerous. In our accounts, we regularly see Performance Max ROAS reported well above like-for-like Search, but the gap is flattered by brand and Shopping cannibalisation. The Google Ads API cannot prove incrementality, and the ROAS figure rests on the same conversion value that is often distorted in the first place. A clean read matters here, which is why we push clients towards a proper conversion funnel analysis for PPC before trusting the headline number.
Automated creative changes get judged through those same measurement pipes. If brand demand, Shopping overlap, poor conversion value mapping or soft leads are already inflating Performance Max, AI-resized videos get rewarded for the wrong reasons. The account tells you the asset is working. The business feels less convinced when margin, lead quality or repeat purchase rate fails to follow.
The creative risk is commercial, not cosmetic
A resized video that looks slightly awkward is not the main issue. The real risk is loss of meaning. Product scale changes when a shot is extended badly. On-screen text becomes cramped. A compliance disclaimer falls outside the safe area. A model, product pack or before-and-after visual gets reframed in a way the brand never approved.
That hits regulated advertisers hardest. Finance, healthcare, supplements, beauty claims, property and B2B software all rely on details being presented correctly. A generated version that preserves the general look but shifts the emphasis creates approval risk and conversion risk at the same time. If you operate in a controlled sector, keep our practical guide to UK advertising regulations next to your creative sign-off process.
For ecommerce, the issue is margin allocation. A resized video for a high-volume, low-margin product line looks attractive to Smart Bidding if conversion value is messy. If the asset helps the wrong product group scale, your account reports revenue growth while profit goes backwards. That is why asset strategy and feed strategy need to meet, especially for retailers already deciding how much budget belongs in Standard Shopping versus PMax.
PPC Geeks’ View
The specific problem UK advertisers will face is unaudited creative expansion. The generated video version will sit inside a campaign that already has limited placement visibility, blended asset reporting and conversion-based bidding. If nobody owns approval after the resize, your media spend becomes the QA process.
We see this most often in ecommerce and lead-gen accounts where Performance Max has been allowed to scale because the headline ROAS or CPA looks acceptable. The asset group structure is usually too broad, the brand and non-brand contribution is blurred, and video assets are treated as supporting material rather than active spend drivers.
Performance Max creative automation is useful only when the account has strict asset rules, clean conversion value and a human review loop. Without that, Google is not filling creative gaps, it is filling control gaps.
— Rory Bettany, Senior PPC Account Manager, PPC Geeks
The immediate takeaway is to assign ownership. Someone in the PPC team must approve generated aspect ratios against the campaign goal, not against whether the video merely looks acceptable. A vertical version for prospecting has a different job from a square version used around remarketing-heavy inventory.
This is exactly the type of issue we look for in a free Google Ads audit, especially where automation, tracking or campaign structure is affecting performance. If your team needs deeper support across asset governance and bidding structure, our Google Ads agency team works through these checks inside live accounts.
How to control PMax video resizing next
Do not treat PMax video resizing as a setting to accept or reject once. Treat it as a new production workflow inside Google Ads. The following checks are practical and should happen before the system gets more freedom with your creative.
- Export your active PMax video assets this week. List every video by campaign, asset group, format, product category, funnel role and approval owner. If the same video supports prospecting, remarketing and branded demand, split the asset logic before judging performance.
- Create a ratio approval grid. Mark which assets are allowed to run in horizontal, vertical and square formats. Product demos, legal-copy-heavy videos and testimonial clips need stricter approval than brand mood films. Use the original report on generative AI video resizing in Performance Max as the trigger for this specific review.
- Check your Performance Max asset settings. Open the relevant PMax campaigns and review video enhancement controls before scaling spend. Google’s own guidance on Performance Max asset groups and assets confirms that assets sit at the centre of how these campaigns run across inventory.
- Build a brand safety checklist for generated formats. Include logo position, product accuracy, mandatory disclaimers, text safe zones, person or product cropping, colour treatment and claim wording. For regulated UK sectors, add ASA and internal compliance sign-off before the asset remains active. The CAP Code for non-broadcast advertising still applies to every reframed variant.
- Segment reporting by asset group purpose. Do not let all video assets sit in one mixed asset group. Separate high-margin products, lead quality tiers, locations or service lines where the creative message differs. That makes any performance change from generated video easier to isolate.
- Run a 14-day creative holdout. Keep one comparable PMax asset group on approved manual ratios only, and allow generated ratios in another where brand risk is low. Judge the test on conversion value quality, assisted brand uplift, lead outcome and margin, not headline ROAS alone.
- Refresh your YouTube creative rules. Vertical and square variants need their own opening three seconds, framing and call to action. Use our YouTube ads best practices guide to pressure-test whether your original creative survives the format change.
There is one control we would not skip: screenshot the generated previews and store them with approval notes. When performance changes three weeks later, you need to know which creative version was live, who approved it, and what it was meant to achieve.
What this means for your campaigns
PMax video resizing is a useful feature for advertisers with disciplined asset governance. It is a risk for advertisers using Performance Max as a black box. The difference is not the technology. The difference is whether your campaign structure, conversion tracking and creative review process are strong enough to stop automation scaling the wrong signal.
Our view is clear: accept the efficiency, but do not outsource judgement. Google can create missing ratios faster than your studio. It cannot know whether a reframed product shot damages trust, whether a disclaimer is legible enough for your compliance team, or whether a strong reported ROAS is hiding cannibalised demand.
If you are unsure how exposed your campaigns are, a free PPC audit will surface the practical gaps quickly.
Frequently asked questions
What is PMax video resizing?
PMax video resizing is Google Ads using generative AI to adapt existing Performance Max video assets into missing aspect ratios, such as vertical or square versions, so they qualify for more placements.
Should UK advertisers opt out of AI video resizing?
Advertisers with strict brand rules, regulated claims, detailed product shots or legal text should opt out or pause the setting until they have reviewed the generated versions. Lower-risk brand awareness assets can be tested with a clear approval process.
How does AI video resizing affect Performance Max results?
It increases the inventory a video asset can enter. If conversion tracking and asset group structure are weak, spend shifts towards generated versions that look efficient in Google Ads but do not improve margin, lead quality or incremental revenue.
What should PPC teams check first?
Start with active PMax video assets. Map each asset to its campaign, asset group, product or service line, funnel role and approved aspect ratios. Then review whether generated versions need brand or compliance sign-off.
Does this replace proper video production?
No. It fills format gaps, but it does not replace creative strategy. Strong vertical video still needs its own framing, pacing, opening hook and call to action. AI-resized assets should be treated as variants, not finished creative by default.
