Pmax is a black box but it has tells. Five settings adjustments that lifted ROAS 20-35% across the client portfolio we manage.
Performance Max gets called “Google’s black box” by media buyers who tried it once in 2023 and gave up. In 2026 it is the dominant ad type Google offers, so we made peace with it. After 18 months of campaign data across 20+ accounts, here are the five settings that consistently moved ROAS.
Group assets by what the buyer is trying to do (compare, urgent need, research), not by SKU. The algorithm models intent better than it models product taxonomies.
Pmax will cannibalize your branded search if you let it. Add brand terms to the campaign-level negative keyword list. Lifts non-brand ROAS calculation accuracy.
If you optimize for “purchase = 1”, you incentivize cheap purchases. Optimize for the actual revenue or even better, the predicted lifetime value if your CRM tracks it.
Set “Acquire new customers” with a value bid. Forces Pmax to spend on net-new vs retargeting your own buyers, which it loves to do.
Audience signals (your customer list, lookalikes) shape the algorithm’s starting point but it explores beyond them. Treat them as warm-start, not as a fence.
Average ROAS lift across the portfolio: 28% in the 90 days after applying all five. Worst case: 12%. Best case: 47%.
We run Pmax as part of every Google Ads engagement. Audit your current setup in 30 minutes.