How Performance Max works
Instead of one campaign per channel, Performance Max takes a single budget and a single goal and distributes them across Search, Shopping, YouTube, Display, Discover, Gmail and Maps. Google decides which channel, which format and which person, and the advertiser supplies the raw material rather than the placements.
That raw material is an asset group: headlines, long headlines, descriptions, images in several shapes, a logo and, where possible, video. Google assembles combinations to suit each surface, and generates a basic video itself if none is supplied. Alongside the assets you add audience signals, which are suggestions about who is likely to convert — your customer lists, site visitors, and interest or search-behaviour segments. They are hints for the system to start from, not targeting rules that limit delivery.
Retail accounts add a product feed from Merchant Center, and products are organised into listing groups so that budgets and targets can differ by product set. Bidding is always conversion-led: maximise conversions or conversion value, with an optional target cost per action or return on ad spend. A few controls remain outside the automation — account-level negative keywords, brand exclusions, location and language, and the ability to exclude certain content types.
Why Performance Max matters
It is now the default route to Shopping inventory and a large share of Google’s other surfaces, so most advertisers meet it whether or not they went looking for it. Its appeal is coverage: one campaign reaches people searching, browsing, watching and shopping without separate builds for each.
Its cost is visibility. Reporting is far thinner than in a search campaign — you see asset group performance and search themes rather than a full account of which query, placement or audience produced each conversion. That trade is acceptable when conversion data is clean and plentiful, and dangerous when it is not, because the automation optimises confidently towards whatever it has been told counts as success.
Common mistakes with Performance Max
The most expensive is running it over weak conversion tracking. If form views, page visits or duplicate events are recorded as conversions, the system will find more of exactly those, and spend rises while enquiries do not.
The second is letting it absorb branded searches. Without brand exclusions or account-level negatives, a Performance Max campaign can take credit for people who were already looking for you and report an excellent cost per acquisition that reflects existing demand rather than new business. The third is starving it: too few assets, no video and one thin audience signal leave the system with little to work with. The fourth is judging it too early, before the learning period has settled.
How to act on it
Fix measurement before launching, so that only genuine business outcomes are counted and values are attached where revenue differs by product or service. Add brand exclusions from the start and decide deliberately whether branded traffic belongs here or in a separate search campaign.
Supply the full set of assets, including at least one real video, and build audience signals from customers rather than from all site visitors. Then leave it alone long enough to exit learning, and review asset groups, listing groups and search themes rather than the campaign total. The mechanics and controls are set out further on the Performance Max campaign page.