PPC expert test: brand exclusions in PMax cut reported conversions 40% — revenue flat
A controlled account experiment suggests a large share of PMax 'performance' is brand demand it didn't create.
- Single-account experiment, 6 weeks, brand terms excluded from PMax
- Reported PMax conversions dropped ~40%; total account revenue unchanged
- Brand search campaigns picked up the demand at a fraction of the CPC
- Blended CAC improved 23% once brand was measured separately
One account, six weeks, so treat this as a signal, not a law. But it matches what I've seen every time I've run this exact test. PMax is brilliant at taking credit for demand that already existed, and the platform has no incentive to make that obvious. The uncomfortable question this raises: if 40% of your PMax conversions would have happened anyway, what is your actual marginal acquisition cost on the other 60%? Usually double what the dashboard implies. Run the brand exclusion test yourself before your next budget review, it's the cheapest incrementality test in PPC.
Questions people ask
Why did my Performance Max conversions drop after excluding brand searches?
Excluding brand searches can reduce reported Performance Max conversions because the campaign loses access to people already searching for your business. In this six week account test, reported PMax conversions fell about 40%, but total account revenue stayed flat as brand Search picked up the demand. That would make me question how much acquisition PMax was actually delivering before defending its budget.
Does excluding brand from Performance Max improve customer acquisition cost?
Brand exclusions can improve blended customer acquisition cost if brand Search captures the same demand more cheaply without reducing total customer acquisition. This account reported a 23% improvement in blended CAC, but one account is not enough to promise the same result elsewhere. I would check total spend and new customers in the CRM before treating a cheaper campaign conversion as better business.
How do I test whether Performance Max is taking credit for branded searches?
Test brand exclusions in Performance Max while keeping brand Search available to capture that demand, then compare total account revenue and blended CAC rather than PMax conversions alone. Keep other major budget and bidding changes out of the test where possible, and allow for conversion lag. I would also watch brand Search impression share, because a budget limited campaign could turn a useful test into lost sales.
Does a 40% drop in Performance Max conversions mean those conversions would have happened anyway?
No, a 40% drop in reported PMax conversions does not prove that all those conversions would have happened anyway. Flat account revenue alongside brand Search picking up demand supports that interpretation, but a six week test in one account cannot establish an exact incremental acquisition cost. For the next budget review, I would want to see whether the remaining PMax spend brings in new customers at a cost the business can afford.
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