Industry estimates consistently put wasted Google Ads spend at around 20% of total budget. That’s not a rounding error. For a business spending £5,000 a month on ads, it means roughly £1,000 going to clicks that were never going to convert. The culprit, more often than not, is a lack of negative keyword management. Not the concept itself, which most advertisers understand at a surface level, but the absence of a structured, repeatable process for finding and plugging the leaks.
This guide isn’t another “what are negative keywords” walkthrough. It’s an operational framework for auditing your negative keyword lists, building a maintenance cadence, and understanding how negatives work differently across campaign types. If you’re running Google Ads and haven’t reviewed your search terms report in the last fortnight, this is where to start.
What Are Negative Keywords and Why Do They Matter?
Negative keywords tell Google which search terms you don’t want your ads to show for. Add “free” as a negative, and your ads won’t appear when someone searches for “free accounting software” even if you’re bidding on “accounting software.” Simple enough in principle.
Where it gets interesting is scale. A well-managed Google Ads account might have hundreds or even thousands of negative keywords across campaigns and shared lists. That’s not overkill. It’s what happens when you systematically review search terms data over time and build negatives based on what you actually see, rather than guessing at launch and forgetting about it.
The impact is direct. Proper negative keyword management can reduce wasted spend by somewhere in the range of 20-35%, according to industry data. That’s not just a CPC saving. It’s a click-through rate improvement (because your ads show to more relevant audiences), a conversion rate improvement (because the traffic is better qualified), and a Quality Score improvement (because relevance goes up across the board).
The Three Negative Keyword Match Types
Google Ads offers three match types for negative keywords, and they work differently from positive keyword match types. This catches people out.
Negative Broad Match
The default. Blocks your ad when the search contains all the words in your negative keyword, in any order. Add free software as a negative broad match and your ad won’t show for “free accounting software” or “software downloads free.” It will still show for “free” on its own or “software” on its own, because both words need to be present.
One thing that catches people out: unlike positive broad match, negative broad match doesn’t cover synonyms or close variants. “Cheap” as a negative won’t block “inexpensive” or “affordable.” You’d need to add each separately.
Negative Phrase Match
Blocks your ad when the search contains the exact phrase in the exact order. Add “free trial” as a negative phrase match and it blocks “free trial accounting software” and “best free trial offers.” It won’t block “trial free” because the word order doesn’t match.
Negative Exact Match
The most precise. Blocks your ad only when the search matches the negative keyword exactly. Add [free accounting software] as a negative exact match and it only blocks that exact search. “Free accounting software UK” still gets through.
Which Match Type Should You Default To?
Broad match for most negatives. Phrase match when you need to block a specific word combination without catching useful single-word queries. Exact match only when a broad or phrase negative would over-block legitimate traffic. Mix them based on the situation.
How to Find Wasted Spend in the Search Terms Report
The search terms report is where you’ll find the actual queries triggering your ads. It’s the single most important data source for negative keyword decisions.
Pulling the Report
In Google Ads, navigate to Insights and reports > Search terms. You can filter by campaign, ad group, date range, and various performance metrics. For a negative keyword audit, start with the last 30 days of data.
What to Look For
Sort by spend (highest first) and work down the list. You’re looking for three types of waste:
Completely irrelevant queries. Someone searching “free Google Ads course” when you sell Google Ads management services. These are obvious. Add them as negatives immediately.
Relevant-sounding queries that never convert. “Google Ads tutorial” might trigger your ads if you’re bidding on Google Ads terms, but someone looking for a tutorial isn’t buying management services. If a query has significant spend and zero conversions over a meaningful time period, it’s a candidate.
Queries with poor efficiency. Some terms convert, but at an unacceptable cost per acquisition. If your target CPA is £50 and a search term runs at £200 per conversion, that’s worth investigating (though it might be a bid or landing page issue rather than a negative keyword situation).
The Hidden Terms Problem
Google doesn’t show you every search term. A growing portion of queries get grouped under “other search terms” for privacy reasons. You won’t find every wasted click in the report. But patterns in the visible data often reveal category-level negatives that cover the hidden terms too. If you notice multiple variations of “jobs” or “careers” showing up, adding those words as negatives will block both the visible and hidden variants.
Campaign Level vs Ad Group Level Negatives
You can apply negative keywords at two levels, and the choice matters more than most advertisers think.
Campaign-Level Negatives
Block a term across every ad group in that campaign. Use these for terms that are irrelevant to anything in the campaign. If none of your ad groups should trigger for “free,” add it at campaign level.
Ad Group-Level Negatives
Block a term for a specific ad group only. This is useful for traffic sculpting. If you have separate ad groups for “accounting software small business” and “accounting software enterprise,” you might add “enterprise” as a negative to the small business ad group and vice versa. The query still triggers ads, just from the correct group.
When to Use Each
Campaign-level for universal irrelevance. Ad group-level for internal routing. Most negatives should be campaign-level. Ad group-level is a refinement tool, not the first line of defence.
One warning: ad group-level negatives can create conflicts. A broad match negative at ad group level that accidentally blocks a keyword in that same ad group will silently kill your reach. Google won’t alert you. Check for conflicts after adding ad group negatives.
Shared Negative Keyword Lists
Shared lists let you create a set of negative keywords once and apply it across multiple campaigns. They’re managed under Tools > Shared library > Negative keyword lists in Google Ads.
The Themed Lists Approach
Rather than one massive list, build themed lists that you can apply selectively:
Universal negatives. Terms that are never relevant to any campaign: “free,” “jobs,” “careers,” “salary,” “DIY,” “tutorial,” “course,” “download.” Every campaign gets this list.
Industry-specific negatives. If you’re in B2B software, you might have a list for consumer-oriented terms: “personal,” “home use,” “family,” “student discount.” Apply it to all B2B campaigns.
Competitor negatives (optional). Some advertisers choose not to show for competitor brand searches. If that’s your strategy, a shared list of competitor brand names keeps it manageable.
Service exclusions. If your business offers SEO but not web design, a list containing “web design,” “website builder,” “WordPress developer” prevents bleed from related-but-wrong queries.
Why Themed Lists Beat One Big List
Modularity. When you launch a new campaign, you apply the lists that are relevant rather than combing through a single 2,000-keyword list wondering which ones matter. Quarterly reviews are faster too, because you can evaluate each themed list against its purpose. Shared lists support up to 5,000 negatives per list with up to 20 lists per account, so capacity isn’t a concern.
How Negatives Work Differently by Campaign Type
This is where a lot of advertisers get caught out. Negative keywords don’t behave the same way across all Google Ads campaign types.
Search Campaigns
Full negative keyword support. All three match types work as described above. You can add negatives at campaign level, ad group level, and via shared lists. This is the most straightforward implementation.
Display Campaigns
Negative keywords work, but differently. On the Display Network, Google uses negatives to influence topic and contextual targeting rather than blocking specific search queries (there aren’t any). Adding “free” as a negative in a Display campaign tells Google to avoid showing your ads on pages where “free” is a prominent topic or theme. It’s less precise than Search negatives and more of a directional signal.
Don’t expect the same surgical precision you get in Search. Display negatives are about avoiding broad content categories, not blocking individual queries.
Shopping Campaigns
Shopping campaigns don’t use traditional keywords. Google matches your product feed to search queries automatically, which makes negatives your only lever for query refinement. Common Shopping negatives include competitor brand names, “used,” “refurbished,” “cheap” (if you’re premium), and product types you don’t carry.
This is where negative keywords can be most valuable pound-for-pound. Review Shopping search terms reports frequently. The algorithm’s matching can be broad, and you’ll regularly find queries technically related to your products but with zero purchase intent.
Performance Max (PMax)
Performance Max historically had very limited negative keyword support. Google has gradually opened this up, and you can now add account-level and campaign-level negatives for PMax. But you can’t add ad group-level negatives (PMax doesn’t have traditional ad groups), and the search terms data available is less granular than standard Search campaigns.
The practical advice: apply your universal negative keyword list at account level so it covers PMax. Monitor whatever search terms data PMax makes available. Accept that you’ll always have less query control here than in Search. That’s the trade-off.
Building a Negative Keyword Audit Process
A one-off clean-up is useful but temporary. Without a recurring process, your negative keyword lists go stale within weeks as new search queries emerge. Here’s a three-tier cadence.
Weekly: Search Terms Review
Every week, pull the search terms report for the past seven days across your active Search and Shopping campaigns. This takes 15-30 minutes once you’ve built the habit.
What to do:
Sort by spend, highest first
Flag any irrelevant terms spending above your threshold (set this based on your budget – £5 wasted might matter for a £500/month account, not for a £50,000/month account)
Add obvious negatives immediately
Log borderline terms for the monthly review rather than making snap decisions
Check that newly added negatives from the previous week haven’t caused unintended blocking
Weekly reviews catch fresh waste early. A new trending search term or a shift in how Google interprets your keywords can send irrelevant traffic your way overnight. Catching it in week one rather than month three is the difference between £50 wasted and £600 wasted.
Monthly: List Review and Expansion
Once a month, step back from individual search terms and review your negative keyword lists as a whole.
What to do:
Review the borderline terms you logged during weekly checks. With a month of data, patterns become clearer. Is “consultant” consistently irrelevant, or did it just have a bad week?
Check your themed shared lists against any new campaigns or ad groups launched that month. Did the new campaign get the right lists applied?
Look at the search terms report for the full 30-day window. Some irrelevant queries won’t appear in any single week’s data but show up when you widen the range.
Cross-reference your negative keywords with your actual keyword list. Make sure no negatives are blocking terms you’re actively bidding on. Google won’t always warn you about this.
Quarterly: Pruning and Strategy Review
Every three months, audit your negative keyword lists for over-blocking and strategic alignment.
What to do:
Pull impression share data for your core campaigns. If impression share has been declining and your bids haven’t changed, over-aggressive negatives might be the cause.
Review any exact match negatives you added. Are they still relevant, or has the search behaviour shifted?
Check for negatives that made sense when added but no longer apply. If you’ve expanded your service offering, terms you previously excluded might now be relevant.
Evaluate whether your themed lists still make sense as categories. Merge or split lists if they’ve become unwieldy or too granular.
Remove any negatives that are clearly redundant. If you have “free download” as a phrase match and “free” as a broad match, the phrase match isn’t doing anything the broad match doesn’t already cover.
Common Negative Keyword Mistakes
Over-Blocking with Broad Match Negatives
Adding “management” as a broad match negative because you saw “project management software” in your search terms report. Problem: you also bid on “Google Ads management services.” That negative just killed your best keyword. Broad match negatives are powerful but blunt. Always check your active keyword list before adding one.
Using Only One Match Type
Some advertisers add everything as broad match. Others add everything as exact match. Broad-only leads to over-blocking. Exact-only leads to whack-a-mole, where you’re adding individual query after individual query while the same category of junk traffic keeps coming through in slightly different forms.
Use the right match type for the situation. Block a category? Broad. Block a phrase without catching its individual words? Phrase. Block one specific query and nothing else? Exact.
Set-and-Forget
The most common mistake by far. An account gets set up, someone adds a handful of obvious negatives like “free” and “jobs,” and then nobody looks at the negative keyword lists again for months or years. Meanwhile, search behaviour changes, new queries emerge, and the account quietly haemorrhages budget on terms that would be obvious negatives to anyone who looked.
Negatives are not a launch-day task. They’re an ongoing process.
Not Checking Across Campaign Types
Adding negatives to your Search campaigns but forgetting about Shopping. Or assuming your PMax campaigns are somehow handling this on their own (they’re not, at least not reliably). Every campaign type that supports negatives needs its own review process.
Adding Negatives Based on Assumptions, Not Data
Guessing which terms to exclude before you have search terms data leads to over-blocking. “Cheap” seems like an obvious negative for a premium brand, but if “cheap” queries are actually converting profitably, you’ve just cut off a revenue stream based on a hunch. Let the data tell you what’s wasting money. Then act on it.
Signs You’ve Gone Too Far with Negatives
Negative keywords can be overdone, and the symptoms aren’t always obvious.
Impression Share Dropping Unexpectedly
If your search impression share is declining and you haven’t reduced bids or budget, check whether recently added negatives are blocking more than intended. Pull the search terms report and compare it to the previous period. If you’re seeing significantly fewer search terms altogether, your negatives may be too aggressive.
In Google Ads, check Campaigns > Columns > Competitive metrics > Search impression share and Search impression share lost (rank). If “lost (rank)” hasn’t increased but overall impressions are down, it’s more likely a negative keyword issue than a bidding issue.
Eligible Terms Being Blocked
Sometimes a broad match negative blocks a keyword you’re actively bidding on. Google won’t always flag this. The symptom is a keyword that suddenly stops getting impressions despite adequate bids and budget. Check the affected keyword’s status and review whether any campaign-level or shared list negatives could be interfering.
Efficiency Not Improving Despite Adding Negatives
If you’ve been aggressively adding negatives but conversion rate and CPA haven’t budged, you might be cutting good traffic alongside bad. A healthy negative keyword process reduces cost faster than it reduces conversions. If both are dropping at the same rate, you’re cutting productive traffic, not waste.
Seasonal Negative Keyword Management
Search behaviour shifts with the calendar, and your negative keyword lists should shift with it.
Retail and e-commerce. During Black Friday and Christmas, terms like “deals,” “discount,” and “sale” might be searches you want to capture rather than block. If “sale” is on your standard negative list, you’ll miss high-intent seasonal traffic. Review and temporarily remove seasonal negatives before major trading periods, and reinstate them after.
B2B and professional services. Summer and Christmas holidays often bring a wave of “intern,” “placement,” and “graduate” searches mixed in with your commercial terms. Add seasonal negatives for these during known low-intent periods.
Education and training. September intake periods change search intent significantly. “Course” might be high-intent in June and low-intent in January for certain programmes.
Events and awareness weeks. National events can temporarily shift search behaviour, generating informational searches that look like your commercial terms but have completely different intent.
Build a seasonal calendar noting which negatives need pausing or activating at which points in the year. Set reminders so this doesn’t rely on someone’s memory.
Measuring the Impact of Negative Keywords
You’re putting time into this process. Make sure it’s paying off by tracking the right metrics.
Click-Through Rate (CTR)
Remove irrelevant impressions and your CTR goes up because the remaining impressions are more relevant. Track CTR at campaign level before and after significant negative keyword additions. Even a 0.5-1% CTR increase can reduce CPCs through Quality Score improvements.
Cost Per Click (CPC)
Better relevance leads to better Quality Scores, which leads to lower CPCs for the same positions. Not always immediate, but over a month or two properly managed negatives should contribute to a downward CPC trend.
Conversion Rate
The metric that matters most. Better-qualified traffic converts at a higher rate. Track at campaign level, period over period.
Wasted Spend Reduction
Calculate this directly. Each week when you review search terms and add negatives, note the total spend on those terms. Sum it monthly. That cumulative figure is the clearest justification for the time invested.
Cost Per Acquisition (CPA)
The combined effect of better CTR, lower CPC, and higher conversion rate should show up as a lower CPA. “We reduced CPA by 15% through negative keyword management” is the kind of concrete result stakeholders actually care about.
Making This Stick
The difference between accounts that waste 20% of budget and accounts that waste 5% isn’t knowledge. Most advertisers understand what negative keywords are. It’s process. A weekly search terms review, a monthly list audit, a quarterly prune. Fifteen minutes a week and an hour a month. That’s all it takes to turn negative keyword management from something you vaguely know you should do into something that’s actually saving you money every single week.
