Performance Max vs Demand Gen: How to Split Budget and Test

On October 14, 2026, Google announced that advertisers will be able to rank channels as high or low priority across Search, Shopping, Performance Max and Demand Gen, and cap how much of the daily budget the low-priority ones get. “Channel prioritization lets marketers decide where their budgets go first,” Google wrote in its announcement, adding that the caps work “on a best-effort basis” and are rolling out “over the next months.” A week earlier, Google opened Conversion Lift studies to Search and Performance Max, Search Engine Land reported.

Performance Max is no longer a black box. The question that remains is whether it finds new customers or collects credit for sales you would have made anyway.

What Performance Max shows you

• Where spend goes. Channel performance reporting, with cost by channel, became “available in all Performance Max campaigns” in November 2025, according to Google’s help page.
• What people searched. Search terms reporting and campaign-level negative keywords and lists are available in all Performance Max campaigns, Google said in an August 2025 update.
• Who it reaches. Since January 2026 you can exclude customer lists and see placement and demographic reports, per Google’s 2026 update.

Switching off Search Partners and Display is still a pilot “with a limited group of advertisers,” PPC Land reported in July 2026.

Three checks for recaptured demand

1. Brand searches. Open the search terms report and add up spend and conversions on your brand name. Overlap is common: across 511 accounts, Performance Max and Search campaigns showed ads for the same search terms in 97.26% of accounts, Optmyzr found in a 2025 study. Where conversion rates differed, Search usually converted better. Brand exclusions “can be leaky,” Search Engine Land wrote, covering a talk by Mike Ryan of Smarter Ecommerce, so add brand negatives for a strict split.

2. Existing customers. Turn on new-customer reporting and check the share of conversions from returning buyers. Google’s customer lifecycle goals can bid higher for new customers or, in a “new customer only” mode, which Google recommends “only if you have strict budgets for customer acquisition,” target them alone.

3. Channels. In the channel report, compare spend on Search and on ads using product data (Shopping) with YouTube, Discover, Gmail and Display. A campaign that spends mostly on brand searches and past visitors is harvesting, whatever its return on ad spend says.

How to split budget with Demand Gen

Google publishes no recommended split. Its case for adding Demand Gen is that it “delivers 10% higher ROAS and 12% higher sales effectiveness” on average, from a Nielsen marketing mix analysis Google commissioned in 2024, according to its Uplift Experiments page. The footnote describes a 2022 to 2024 study of Search ads and doesn’t break out Performance Max. Optmyzr’s study of 24,702 Performance Max campaigns found “potential conversion rate and CPA advantages when keeping PMax limited to 10%–25% of the budget,” in its analysis, a correlation rather than a test.

A practical start: fund Demand Gen at the level Google recommends, at least 10 times your target cost per acquisition per day, and judge it on incremental sales and new customers rather than last-click return. Our guide to Demand Gen campaigns covers setup and budgets.

Which test to run

• Demand Gen Uplift Experiments. An automated A/B test, launched in May 2026, of adding Demand Gen to an existing Performance Max mix. Google hasn’t published minimum requirements.
• Conversion Lift. A holdout of users who don’t see the ads, needing a $5,000 minimum budget and at least 1,000 observed conversions, with studies of at least 7 days and Google recommending more than 14, according to its help page. Availability varies by account.
• Brand exclusion test. Google has no experiment type for it. Exclude your brand from Performance Max for a set period or region, and watch total sales and branded Search conversions.

Our guides to incrementality testing and what you can still control in Google Ads cover the rest. Running these tests is part of our performance marketing and ecommerce marketing work.

Frequently Asked Questions

Is Performance Max still a black box?

Much less than it was. Since 2025 Google has added channel performance reporting with cost by channel, search terms reporting, campaign-level negative keywords, customer list exclusions and placement and demographic reports. Channel budget caps are rolling out from October 2026. What it still doesn’t show directly is how many of its sales would have happened anyway, which needs a holdout test.

Should I run Demand Gen alongside Performance Max?

If Performance Max spends mostly on brand searches and past visitors, adding Demand Gen is a reasonable way to reach people who don’t know you yet. Google says advertisers adding Demand Gen saw higher return on ad spend, based on a study of Search ads it commissioned, which doesn’t break out Performance Max. Test it with Google’s Demand Gen Uplift Experiments or a Conversion Lift study.

How should I split budget between Performance Max and Demand Gen?

Google gives no recommended split. Fund Demand Gen at the level Google says it needs, at least 10 times your target cost per acquisition per day, and judge it on incremental sales rather than last-click return. One Optmyzr study found better conversion rates and costs where Performance Max took 10% to 25% of budget, but that is a correlation, not proof.

How do I know if Performance Max is cannibalizing my brand search?

Check the search terms report for brand queries and the share of conversions from returning customers. Then test: exclude your brand from Performance Max with brand exclusions and negative keywords for a set period or region, and compare total sales and branded Search conversions. If total sales hold steady, Performance Max was mostly taking credit for searches you would have won anyway.