Performance Max vs Search Campaigns: Who Actually Wins When Both Match the Same Query?

You launch a Performance Max campaign. A few weeks later your Search campaign’s impression share has slipped, Performance Max is reporting a healthy ROAS, and total conversions are roughly flat. Somebody on the team says Performance Max is “eating” Search. Somebody else says it’s finding new customers. Both are looking at the same dashboard, and neither can prove anything from it.

This is one of the most common arguments in Google Ads right now, and it usually gets settled by whoever argues more confidently. That’s a poor way to decide where a few thousand dollars a month goes. The question has a real answer, or at least a real way of finding the answer in your own account, and the first step is understanding what Google actually does when a single search query could trigger more than one of your campaigns.

This post walks through the documented rules, what the larger overlap studies found (and where they disagree), how to test your own account without guessing, and what to do with brand terms, negatives and structure once you know what’s happening.

The rule Google documents for overlapping campaigns

When someone searches, Google runs one auction per advertiser for that query. It doesn’t let your own campaigns bid against each other in the open auction the way two competitors would. Instead it picks which of your campaigns gets to represent you, and the rule it uses for Search versus Performance Max is more specific than most people assume.

As Google’s help documentation describes it, and as summarised by outlets such as Search Engine Journal, the order works like this:

• If the search query is identical to a keyword in one of your Search campaigns, that Search keyword takes priority over Performance Max. This holds even when the keyword is phrase or broad match, as long as the query text is the same as the keyword text.
• If the query is not identical to any keyword, but matches a Performance Max search theme and also matches a phrase or broad match keyword through close variants, the winner is decided by Ad Rank. Search themes carry the same priority as phrase and broad match keywords.
• If nothing in your Search campaigns matches the query, Performance Max is free to take it.

The practical reading is that Search campaigns win automatically only when there’s an exact textual match between the query and one of your keywords. For everything else, which is most of the long tail, Performance Max and Search can both be eligible, and the better Ad Rank takes it. Ad Rank here is the same blend of bid, expected click-through rate, ad relevance and landing page experience that decides every auction. If you want to refresh how those pieces fit together, our piece on what Quality Score actually measures covers the inputs.

Notice what this does not say. It doesn’t say Search always wins, and it doesn’t say Performance Max always wins. It says there’s a defined priority for exact matches and an auction for everything else. Whatever you’ve heard from a vendor or a forum thread, that’s the foundation.

What the overlap studies actually found

Two data studies get cited constantly in this debate, and they’re often cited as if they agree. They measured different things, so it’s worth being precise.

Optmyzr’s study. Optmyzr looked at 503 accounts using its platform, over February 2025. According to their write-up, 91.45% of those accounts had some keyword overlap between Search and Performance Max. At the campaign level, 56.29% of 5,768 Search campaigns showed overlap, and 27.86% of 40,642 ad groups were affected. They also noted that overlap showed up across all match types, including exact match, so having an exact match keyword for a term doesn’t guarantee Performance Max stays out of it. In the cases they could compare on conversion rate, Search came out ahead in about 19% of overlapping cases, Performance Max in about 6%, and there was no meaningful difference in roughly 75%.

Adalysis’s study. Adalysis analysed more than 3,300 non-retail Performance Max campaigns covering around 1.2 million search terms. They found that 67% of Performance Max campaigns overlapped with a Search campaign for at least one search term. At the individual term level, though, the picture was less alarming: Performance Max ads appeared for search terms matching an exact keyword only about 2.8% of the time overall, with many accounts showing none. Where a term could trigger either campaign type, 45% of the time it triggered both. Among overlapping cases, Search had the higher conversion rate in around 84% of comparisons and the higher click-through rate in around 65%, even though Performance Max won more impressions (43% of the time overall, 61% when you only count campaigns that overlapped).

Read side by side, these studies are describing the same underlying thing from different angles. Overlap is very common. Most of it is not a rule violation, because it involves terms that aren’t exact keyword matches, which is exactly where the rules say an auction decides. And when both campaign types compete for the same query, Search tends to convert better on average, but the size of that gap varies a lot depending on how you slice it. The Optmyzr number says “mostly no difference”; the Adalysis number says “Search usually wins.” Both can be true if the average gap is small but consistent in direction.

Two cautions about these studies. First, both come from companies that sell PPC software, and both come from accounts that use their tools, which probably skews toward more actively managed accounts than the typical advertiser. Second, they describe averages across hundreds or thousands of accounts. Your account isn’t an average. The useful thing they establish is that the overlap is real and worth measuring, not what the answer will be in your case.

Why “cannibalization” is the wrong word half the time

Cannibalization implies that one campaign is stealing from another and the total gets worse. Sometimes that’s what’s happening. Often it isn’t, and it helps to separate three different situations that all look the same in a campaign-level report.

Situation one: the redistribution that costs you nothing. Performance Max takes impressions and clicks from queries that Search was also eligible for, at a similar cost per conversion, and your total conversions and total cost stay about where they were. Search looks worse, Performance Max looks better, and the account is unchanged. This is the most common outcome, and it’s why a campaign-by-campaign view is misleading. You’re watching money move between pockets.

Situation two: the shift to a more expensive route. Performance Max takes queries Search would have handled at a lower cost per conversion, because Search keyword targeting with tailored ad copy and a specific landing page converts better for those queries. Total conversions drop or total cost per conversion rises. Here you really are paying more for the same demand. Brand queries are the clearest example, which gets its own section below.

Situation three: genuine incremental volume. Performance Max reaches queries or placements that your Search keywords never touched, such as long-tail queries, Shopping placements, YouTube or Display. Total conversions go up. Some overlap still exists, but it’s small compared with the new volume. This is the case Google’s pitch is built around, and it does happen, especially in accounts whose keyword lists were thin to begin with.

You can’t tell which of these you’re in by looking at Performance Max’s own ROAS or CPA. Those numbers are attributed within the campaign, and attribution doesn’t know what would have happened without it. What you need is account-level totals before and after, plus a look at which queries each campaign is serving. The next section is how to do that without a data science team.

How to check your own account, step by step

None of this needs special tools. It needs a few reports and the discipline to compare like with like.

Step 1: Establish the account-level baseline

Pick the date Performance Max launched, or the date its budget changed significantly. Compare the four to eight weeks before with the same length of time after, for the whole account (Search plus Performance Max plus anything else). Look at total spend, total conversions, and total conversion value if you track it. If total conversions rose with spend roughly proportional, you’re probably in situation three or a healthy version of situation one. If spend rose and conversions didn’t, keep digging.

Be wary of seasonality and of any other change you made in the same window. If you also changed bidding strategies or rewrote ads, you can’t attribute the shift to Performance Max. Our change history guide shows how to line up what you changed against what moved.

Step 2: Watch impression share on the Search campaigns

Pull the Search campaign’s impression share, and specifically the share lost to rank versus lost to budget, across the same window. When Performance Max starts winning auctions that Search would have won, you’ll often see impression share lost to rank rise on Search even though you didn’t change bids. If instead you see lost-to-budget rising, the cause might just be that Search is running out of money, which is a different problem. Our post on telling budget loss from rank loss goes through how to separate them.

A decline in Search impression share that lines up with a Performance Max launch is the clearest early signal of overlap, but it’s only a signal. It tells you where to look, not what to conclude.

Step 3: Compare search terms across the two campaign types

This is where the actual evidence lives. For Search campaigns, the search terms report has always shown the queries that triggered your ads. Performance Max has historically been murkier. It started with search categories (groupings of queries) through the search terms insights view, and according to recent coverage of Google’s updates, fuller search term reporting for Performance Max has been rolling out since late 2025, bringing it closer to what you get in Search. Google has also added channel-level reporting that shows how Performance Max spend and results split across Search, Shopping, YouTube, Display and other surfaces. Check what your account actually shows, since availability has changed in stages and may differ across accounts.

Once you have query-level data for both, export them and look for terms that appear in both. For each shared term, compare cost per conversion and conversion rate between the two campaigns. You’re looking for two things: queries where Search converts materially better, and queries where Performance Max is the only one serving and converting well. The first group is a candidate for protection. The second group is the incremental volume you want to keep.

If you’re not used to digging through that report, our walkthrough of how to read a search term report covers the columns and the common traps.

Step 4: Separate brand from non-brand

Most of the damage from overlap, and most of the misleading reporting, sits in brand queries. Split the comparison: brand terms in one bucket, everything else in another. A blended result hides the problem. Performance Max can report excellent ROAS largely because it’s collecting people who typed your company name, which would have converted anyway.

Step 5: Decide with a test, not a hunch

If the data is ambiguous, the honest answer is to run a controlled change and see what happens at the account level. For example, apply brand exclusions to Performance Max for a few weeks, then compare total account conversions and cost against the period before. Change one thing at a time. If you want to run this properly, our guide to Google Ads experiments covers how to avoid fooling yourself with a before-and-after that was really just a seasonal blip.

Brand queries: where overlap does the most quiet damage

People searching for your business by name already know who you are. They convert at high rates, and the cost per click is typically low compared with generic queries. If Performance Max serves those clicks, two things happen. You might pay more per click than a dedicated brand Search campaign would have, depending on how your bids and Ad Rank compare. And Performance Max’s reported results look better than they are, because it’s being credited with conversions that were mostly going to happen regardless.

Several practitioner write-ups put numbers on how much worse this can get, but the figures tend to come from agencies describing their own client accounts, so treat them as illustrations, not benchmarks. What’s solid is the mechanism: if brand traffic flows through a campaign that doesn’t isolate it, your reports can’t tell you how much of your performance is brand demand you’d have gotten anyway.

Google provides brand exclusions for this. You create a brand list at the account level, then apply it as an exclusion to individual Performance Max campaigns. A few points about how this works that are easy to miss:

• Brand exclusions apply to Search and Shopping inventory inside Performance Max. They don’t affect Display, YouTube or other surfaces, so someone could still see a Performance Max ad for your brand on those.
• Matching isn’t perfect. Brand lists catch the brand and common variants, but unusual combinations, misspellings or lateral terms can slip through. Writing a small set of negative keywords for the ones you spot in your reports is a sensible backstop.
• You apply the list per campaign. Making a list doesn’t automatically protect every Performance Max campaign you have.

Whether you should exclude brand from Performance Max at all depends on your situation. If you run a dedicated brand Search campaign and care about measuring non-brand performance, exclusion usually makes sense. If you don’t run brand Search at all, and brand traffic is cheap anyway, you may prefer to let Performance Max serve it and accept the blurrier reporting. We looked at the wider question of whether paying for your own name makes sense in our post on bidding on your own brand, and the same logic carries over here: it depends on whether competitors bid on your name and how much of your traffic is brand.

Negative keywords in Performance Max: useful, but narrower than you’d hope

Performance Max supports negative keywords, and there are also account-level negative keyword lists that apply across campaigns. They help in specific ways, and it’s worth being clear about where they stop.

• Negatives in Performance Max only affect Search and Shopping inventory. They don’t touch Display, YouTube, Gmail or Maps placements. So a negative keyword won’t stop an irrelevant Display impression.
• Per-campaign negative keyword limits for Performance Max are generous according to current guidance (figures in the thousands are cited, but confirm the number in your own account since limits have changed over time).
• Negatives are the right tool for keeping Performance Max off terms that clearly don’t belong to it, such as job-seekers, competitors you don’t want to bid on, or products you don’t sell.

The mistake to avoid is trying to use negatives to carve up the whole keyword space between Search and Performance Max. It works poorly in practice. Performance Max doesn’t have keywords in the usual sense, and a negative that keeps it away from a profitable query just removes volume. We covered how to build a list worth maintaining in our guide to negative keywords, and the cautions there apply doubly when you’re working with a campaign type that gives you less visibility.

What exact match keywords can and can’t protect

Because exact match keywords have the strongest priority claim, a common recommendation is to add the terms you care about as exact match keywords in Search. Anything that matches precisely goes to Search, according to Google’s rules.

That advice is right as far as it goes, with two limits. First, as Optmyzr’s study noted, overlap still appeared for exact match keywords, which means you shouldn’t assume the rule gives you airtight protection. Whether that reflects close-variant matching, timing, or something else is hard to know from the outside, and it should make you check rather than trust. Second, exact match is a narrow net by design. It protects the specific queries you list and not the thousands of variations around them, which are exactly the queries where the auction rules apply.

Match types have also changed enough in recent years that “exact” doesn’t mean what it used to. Our write-up on keyword match types in 2026 explains how close variants affect what an exact match keyword really covers. Add the AI-driven broadening in newer Search features (see our post on AI Max for Search campaigns) and the picture gets even less clean: Search itself now has settings that expand matching beyond your keyword list, which adds another source of overlap with Performance Max.

Should you run both? A practical way to decide

There’s no universal answer, and anyone who says there is probably wants to sell you a particular setup. Here’s a way to think about it by situation.

You have a mature Search program with good conversion volume. Keep Search as the foundation, and treat Performance Max as an addition to test, ideally with a modest budget and brand exclusions applied from day one. Measure at the account level. If total conversions at an acceptable cost go up, keep it. If they don’t, you’ve learned that your Search coverage was already good and Performance Max is mostly redistributing.

You’re an e-commerce advertiser with a product feed. Performance Max includes Shopping placements, which Search campaigns can’t reach. That surface is where much of the genuinely incremental volume usually comes from. Overlap on brand and high-intent queries is still worth managing, but the case for running Performance Max is stronger here. If your feed has issues, those will limit Performance Max regardless of how you handle overlap, and we’ve written about feed errors that get products disapproved in detail.

You generate leads with a small budget and limited conversion volume. Performance Max needs conversion data to optimise, like any automated strategy. If you’re only getting a handful of conversions a month, splitting a small budget across two campaigns can leave both starved. Our post on how much conversion data Smart Bidding needs explains why. In that case it’s often better to get Search working properly before adding a second campaign type.

You can’t see what Performance Max is doing and that bothers you. That’s a reasonable position. Reporting has improved, but it’s still thinner than Search. If you want to understand what’s going on inside it, our guide to auditing a Performance Max campaign covers what you can check even with limited visibility, and our piece on audience signals explains one of the few levers you do have.

Mistakes that make overlap worse

Judging by campaign-level ROAS. Performance Max’s ROAS and Search’s ROAS aren’t measured against the same baseline. When both campaigns can serve the same user, attribution decides who gets the credit, and it doesn’t tell you who caused the sale. Compare totals.

Pausing Search because Performance Max looks cheaper. If Performance Max’s lower cost per conversion comes from absorbing brand and other easy conversions, pausing Search removes the thing making those conversions cheap in the first place. Cost per conversion can look good right up until volume falls.

Changing too much at once. Smart Bidding needs time after any significant change. If you adjust budgets, targets, brand exclusions and assets all in the same week, you won’t know what caused the movement afterwards, and you may trigger another recalibration. Our explanation of the learning phase and why edits reset it is worth reading before you start a round of changes.

Leaving conversion tracking messy. If both campaign types optimise toward a conversion goal that includes low-value actions, such as page views or micro-conversions counted as primary, both will chase the wrong thing, and the comparison between them is meaningless. Check that the actions you optimise to are the ones you actually care about. Our guide on auditing conversion tracking is the place to start.

Setting it once and not looking again. Overlap isn’t static. It changes when you add keywords, when Google changes matching behaviour, when competitors move, and when you adjust budgets. A split that was fine in March can look different by June. That brings us to what a monitoring routine should include.

A routine that catches overlap problems early

You don’t need to check everything daily, but a few things are worth checking on a rhythm so you notice drift instead of discovering it after a quarter of lost efficiency. Our post on how often to check your Google Ads account gets into cadence in more depth. For this specific topic, a reasonable routine looks like this:

• Weekly: Check Search impression share and share lost to rank, and compare against Performance Max spend. A sustained shift in one while the other moves the opposite way is a prompt to look at search terms.
• Every two to four weeks: Export search terms from both campaign types, and look at shared queries. Check brand versus non-brand separately. Add negatives for any irrelevant terms that have crept in.
• Monthly: Compare account-level totals (spend, conversions, cost per conversion) with the previous period. Ask whether the combined account is better than it was before Performance Max, not whether Performance Max alone looks good.
• Whenever you change something significant: Write down what you changed and when, and hold off on further changes until you’ve seen enough data to judge the first one.

Some of this can be partly automated with rules and scripts, though they have clear limits. We looked at what those catch and miss in our post on automated rules and scripts. The short version is that a rule can tell you impression share dropped, but it can’t tell you why.

Where continuous monitoring fits

The routine above works, but it relies on someone remembering to run it and noticing patterns across several reports. The tedious part is that overlap problems rarely announce themselves. They show up as a slow change in the ratio between two campaigns’ spend, or a brand term that quietly moved from one campaign to another. Growera’s Google Ads manager watches an account daily, so shifts like a Search campaign losing impression share after a Performance Max change, or a spike in spend on branded queries, get flagged as they happen rather than at the next monthly review. It doesn’t replace the judgement about whether to keep, restructure or pause a campaign. That decision depends on your margins and goals. It just shortens the gap between something changing and you knowing about it. You can see how that works on the ERA AI page, and plan details are on the pricing page.

Summary

When a query could trigger both a Search campaign and a Performance Max campaign, Google applies a defined order: a Search keyword that matches the query exactly takes priority, and for everything else an auction on Ad Rank decides. Overlap between the two campaign types is extremely common across accounts, according to studies by Optmyzr (503 accounts) and Adalysis (3,300+ Performance Max campaigns), though most of it involves queries where the auction rules apply rather than exact-match violations. When both can serve the same query, Search tends to convert better on average, though the studies disagree on how large that gap is.

What that means for you, in order of effort:

• Don’t judge the two campaigns separately. Compare account-level spend and conversions before and after Performance Max.
• Look at Search impression share and share lost to rank for early signs that Performance Max is winning auctions Search used to win.
• Compare search terms between both campaign types, and split brand from non-brand before drawing any conclusion.
• Use brand exclusions and targeted negative keywords where the overlap is clearly costing you, remembering that both only cover Search and Shopping inventory inside Performance Max.
• Test changes one at a time, give them room to settle, and read the result at the account level.
• Re-check regularly, because the balance between the two shifts as your account and Google’s systems change.

Neither campaign type is the villain. The goal isn’t to make Search win or Performance Max win. It’s to make sure that every query is served by the campaign that handles it at the best cost, and that you can see whether that’s really happening.