The budget leak most businesses never find
There's a good chance your Google Ads account is wasting money right now, and you don't even know it. Not because your bids are wrong or your ads are badly written, but because you're showing up for searches that have nothing to do with what you sell.
Negative keywords fix this. They're the list of terms you tell Google not to trigger your ads for. If you sell industrial valves and someone searches "valve replacement heart surgery," you don't want to pay for that click. A negative keyword stops it from happening.
It sounds simple because it is simple. But the number of businesses running Google Ads campaigns without a proper negative keyword strategy is staggering. When we audit PPC accounts, the lack of effective, or even any, negative keyword lists is one of the most common problems we find. Sometimes they haven't been updated in months, and sometimes they're actively blocking searches that should be converting!
This post covers everything you need to know about negative keywords: what they are, how they work, how to find the right ones, and how to avoid the mistakes that cost businesses thousands in wasted ad spend.
What negative keywords actually do
When you run a Google Ads campaign, you bid on keywords. Google looks at what someone types into the search bar, matches it against your keywords, and decides whether to show your ad. The problem is, Google's matching has become increasingly broad over the years. Even "exact match" keywords now trigger for searches Google considers semantically similar, which means your ads can appear for queries you never intended to target.
Negative keywords work in reverse. Instead of telling Google what to show your ads for, they tell Google what not to show your ads for. If you add "free" as a negative keyword, your ad won't appear when someone includes "free" in their search. If you add "jobs" as a negative, you won't show up when someone's looking for employment rather than your services.
Without negatives, you're relying entirely on Google's judgment about which searches are relevant to your business, and that's a terrible idea.
Why does this matter more in 2026 than it used to
Google has been steadily loosening its keyword-matching rules. Broad match is broader than ever; phrase match captures queries it wouldn't have captured a few years ago; and even exact match now includes what Google calls "close variants," which can be surprisingly loose. It's actually surprising they are not challenged on this more often, but if you try, you'll be wasting your time.
On top of that, campaign types like Performance Max and Demand Gen give you less visibility into what searches are actually triggering your ads. Google is pushing advertisers toward automation, and while that automation can work well, and very, very badly, it also means you have fewer manual controls. Negative keywords are one of the few levers you still have to shape where your ads appear.
There have been some positive changes too. In 2025, Google expanded the negative keyword limit for Performance Max campaigns to 10,000 per campaign, up from just 100 previously. They also started applying misspelling variations to negative keywords automatically, so you no longer need to add every possible typo as a separate negative. These are welcome improvements, but they only help if you're actually using negatives properly in the first place.
The three match types for negative keywords
Negative keywords have their own match types, and they work differently from regular keyword match types. This trips up a lot of people, so it's worth understanding properly.
Negative broad match is the default. If you add "free training" as a negative broad match, your ad won't show for any search that contains both "free" and "training" in any order. But it will still show for searches that contain only one of those words. Someone searching "training courses" would still see your ad. Someone searching "free industrial equipment" would also still see your ad. Both words need to be present for the negative to trigger.
Negative phrase match blocks searches that contain your negative keyword phrase in the exact order you specified. Adding "free training" as a phrase match negative blocks "free training courses" and "best free training for engineers," but it wouldn't block "training for free" because the word order is different.
Negative exact match only blocks the precise search term you've specified. Adding [free training] as an exact match negative blocks "free training" and nothing else. Not "free training courses," not "free online training." Just that exact phrase.
Here's the critical difference from regular keywords: negative keywords don't include close variants, synonyms, or related terms. If you add "car" as a negative, Google won't automatically block "automobile" or "vehicle." You need to add each variation separately. This asymmetry catches people out because they assume negatives work the same way as regular keywords, and they don't.
How to find your negative keywords
The single most important habit in Google Ads management is reviewing your search terms report. This report shows you the actual searches that triggered your ads, not the keywords you're bidding on, but what real people actually typed into Google before clicking your ad.
Go to your Google Ads account, select a campaign, click "Insights and reports," then "Search terms." You'll see a list of queries alongside impressions, clicks, and cost data. Some of these will make perfect sense. Others will make you wonder what Google was thinking. If you review this report, I guarantee there will be some WTF moments.
Look for patterns. If you're a B2B engineering company, you'll likely see searches from students doing coursework, people looking for jobs, DIY enthusiasts, and consumers looking for things you don't sell to individuals. These are all candidates for negative keywords.
Here's a practical approach that works well. Review your search terms weekly for the first month of any new campaign, then fortnightly once things settle down. Sort by cost to find the expensive irrelevant clicks first, because those are the ones bleeding your budget fastest. Add negatives as you find them, and build your list over time.
Beyond the search terms report, think about your business and what you explicitly don't offer. If you only work with enterprise clients, add negatives for "small business," "startup," "freelance," and "sole trader." If you don't offer free trials, add "free." If you're B2B only, consider negatives for consumer-intent terms. If you're UK-based and don't serve international markets, you can negative out other country names that appear in irrelevant queries.
The negative keywords every B2B campaign needs
While every business is different, there's a core set of negatives that almost every B2B advertiser should have from day one. These filter out the searches that consistently waste budget across industries.
Job-related terms come first: "jobs," "careers," "hiring," "salary," "vacancy," "recruitment," "CV," "resume," "interview." People searching for employment in your industry will click your ads all day long and never become customers. This is one of the biggest drains on the budget in B2B PPC.
Educational and informational terms are next: "course," "degree," "university," "training," "certification," "how to become," "what is." Unless you sell training services, these searches come from people in learning mode rather than buying mode.
Price-sensitive terms matter if you're not competing on price: "free," "cheap," "budget," "discount," "low cost," "affordable." If your average deal value is £50,000, someone searching for the "cheapest" version of what you offer is almost certainly not your customer.
DIY and consumer terms round it out: "DIY," "homemade," "tutorial," "for beginners," "at home." These indicate someone looking to do it themselves rather than hire a company like yours.
This isn't an exhaustive list, and it's not meant to be applied blindly. You need to think about what makes sense for your specific business. But starting with these categories on day one will save you from the most obvious wasted spend while you build a more tailored list from your search terms data. Your favourite AI tool, given clear instructions, will curate a solid list of negative keywords for you.
How to structure your negative keyword lists
Google Ads lets you create shared negative keyword lists that apply across multiple campaigns. Use them, they're one of the most underused features in the platform.
The approach that works well for most businesses is to have a universal list that applies to every campaign. This contains the negatives that are always irrelevant, regardless of what you're advertising: job searches, competitor brand names you don't want to bid against, completely unrelated industries, and so on.
Then create campaign-specific negatives for terms that are irrelevant to one campaign but not another. If you have separate campaigns for different product lines, a search term that's irrelevant to your valve campaign might be perfectly relevant to your pump campaign. These go at the campaign level, not on the shared list.
You can also use negatives to control which campaign serves which searches. If you have both a broad-match awareness campaign and an exact-match high-intent campaign, adding your high-intent keywords as negatives in the broad campaign prevents them from competing against each other. This gives you cleaner data and more control over which ad copy and landing page someone sees based on their intent level.
The mistakes that cost real money
The most expensive mistake is simply not using negative keywords at all. We've seen accounts spending thousands per month with a completely empty negative keyword list. Every irrelevant click in those accounts was pure waste, and the cumulative cost over months or years is painful to calculate.
The second most common mistake is setting and forgetting. You add a list of negatives when you launch the campaign, then never look at search terms again. Google's matching evolves, your competitors change, and seasonal trends shift what people search for. A negative keyword list that was comprehensive six months ago now has gaps; this needs ongoing attention.
Over-blocking is the opposite problem, and it's surprisingly common in accounts managed by multiple people over time. Someone adds a negative that seems logical in isolation, but it inadvertently blocks searches from genuine prospects. The classic example is adding "engineer" as a negative when you actually sell to engineers. Or adding "used" when you sell refurbished equipment. Always check for conflicts between your negative keywords and your active keywords. Google Ads flags some of these, but not all.
Inconsistent application across campaigns is another issue. Someone adds a negative to Campaign A but forgets about Campaigns B, C, and D. The irrelevant search keeps triggering ads from the other campaigns, and nobody notices because the search terms report is being reviewed at the campaign level. Shared negative keyword lists solve this, which is why they should be your default approach for universal negatives.
Finally, using the wrong match type on your negatives can either leave gaps or block too aggressively. If you're not sure, phrase match is usually the safest default for negatives. It blocks the specific phrase and longer variations of it without accidentally catching unrelated searches, as broad match sometimes can.
How often should you review and update
For new campaigns, review search terms at least weekly for the first four to six weeks. New campaigns attract the most irrelevant traffic because Google is still learning what's relevant to your account, and your negative keyword list is at its thinnest.
For established campaigns, a fortnightly or monthly review is usually enough. Set a recurring task, block out 30 minutes, and go through the search terms report for each active campaign. Look at anything with more than one click that doesn't match your targeting intent. Add negatives as needed.
It's also worth doing a full audit every quarter. Look at your negative keyword lists as a whole. Check for conflicts with active keywords. Remove any negatives that no longer make sense. Make sure shared lists are applied to all relevant campaigns. This kind of maintenance isn't exciting, but it's the difference between a well-optimised account and one that's quietly haemorrhaging budget.
Negative keywords in Performance Max and automated campaigns
Performance Max has been a source of frustration for advertisers who value control, because for a long time, it offered almost none when it came to negative keywords. That's improved significantly.
As of 2025, you can add up to 10,000 negative keywords per Performance Max campaign, and you can use shared negative keyword lists. This is a major change from the original limit of 100, which was practically useless for any serious advertiser.
The catch is that negative keywords in Performance Max only affect the Search and Shopping inventory. They don't influence where your ads appear on YouTube, Display, Gmail, or Discover. So if your PMax campaign is showing ads on irrelevant websites or YouTube channels, negative keywords won't help with that. You need other controls like placement exclusions for those channels.
For Demand Gen campaigns, negative keyword support is more limited, and you'll need to check the current documentation for the latest capabilities because Google updates these features regularly.
The broader point is this: as Google pushes more advertisers toward automated campaign types, negative keywords become one of the few manual controls you retain. Use them aggressively. The alternative is trusting Google's algorithm to decide what's relevant, and if you've ever looked at a search terms report, you'll know that trust isn't always well placed.
Making this work for your business
Negative keywords aren't complicated, but they require discipline. The businesses that manage their PPC budgets well are the ones that treat negative keyword management as an ongoing process rather than a one-time setup task.
Start with the basics. Add the obvious negatives for your industry before you spend a penny on clicks. Review your search terms report regularly and add new negatives as patterns emerge. Use shared lists to keep things consistent across campaigns. Check for conflicts quarterly. Pay attention to match types.
If you're spending more than a few hundred pounds a month on Google Ads and you haven't looked at your negative keywords recently, that's probably the single highest-impact thing you could do this week. The money you save goes straight to your bottom line, or gets reinvested in clicks that actually convert.
We manage PPC for engineering and industrial companies, and negative keyword management is one of the things we're most particular about. If you'd like us to audit your current setup or talk through how to get more from your ad spend, our PPC management service is built specifically for B2B companies where every click needs to count. And if you want a broader context on how PPC fits into an engineering company's marketing, we've written about targeting strategies for industrial clients that cover the wider picture.
