Negative Keywords in Google Ads: How to Stop Paying for the Wrong Searches
A negative keyword list built in your first fortnight and never touched again is the most reliable source of wasted spend in a Google Ads account. Here is the process we use to fix it.
Most Google Ads accounts we audit have a negative keyword list that was built in the first fortnight and never touched again. That is the most reliable source of wasted spend we find, and it is also the easiest thing to fix in an afternoon. Negative keywords in Google Ads are how you tell the platform which searches you never want to pay for, and in an account running broad match with Smart Bidding, that instruction carries far more weight than it did five years ago.
What follows is the process we actually use, rather than a downloadable list of 500 terms you paste in once and forget.
Negatives do not behave like your keywords
A negative keyword makes your ad ineligible for searches containing that term. Straightforward enough. The part that catches people out is that negative keywords do not match close variants. Exclude "flowers" and your ads can still show for "flower". Google's documentation is explicit that negatives only account for casing and misspellings automatically. Plurals, synonyms and stem words all need adding yourself.
That asymmetry is the whole problem. Your targeting expands outwards on its own; your exclusions do not. If you have ever wondered why the same junk term keeps reappearing after you thought you had blocked it, this is usually why.
The match types invert too. A negative broad match blocks only searches containing every one of your terms in any order, so negative broad "running shoes" will not block "shoes" on its own. Negative phrase blocks those terms in that order. Negative exact blocks that search and nothing longer. Most people reach for exact when they mean phrase, then wonder why the variants slip through.
Start with the search terms report, not a template
Generic negative lists have their place. "Free", "jobs", "salary", "DIY" and "how to make" are a sensible floor. But they are the floor, not the work. The real money sits in your own search terms report, which shows the searches that actually triggered your ads and how each one performed.
Pull the last 60 to 90 days, sort by cost descending, and read every term that has spent more than a click or two with nothing to show for it. That list is your brief. Sorting by impressions instead is a common mistake: impressions are free, spend is not.
Bear in mind the report only shows terms searched by a meaningful number of people, so a long tail of low-volume queries stays hidden from you. You cannot block what you cannot see, which is one reason broad match still needs tightly themed keyword sets rather than negatives alone.
Four buckets worth blocking
Wrong intent. Someone researching rather than buying. "What is", "meaning", "template", "example". Depending on your funnel these may be worth keeping, but that should be a deliberate choice with its own budget, not an accident.
Wrong product or service. The classic case. You sell commercial roofing and you are paying for "roof repair near me" from homeowners. These terms look relevant on paper and convert at nothing.
Wrong price point. "Cheap", "budget", "free" and "discount" if you sell at a premium. Blocking these is one of the fastest ways to lift lead quality without touching your bids.
Competitor and job-seeker traffic. Careers searches and people looking for a named rival rarely convert on a generic campaign. Bid on competitor terms deliberately in their own campaign if you want to, but do not let them leak into your core one.
Where to put them
You have three levels, and choosing badly creates a mess that is painful to unwind later.
Account-level negative keywords apply across all search and shopping inventory in Search, Performance Max, Shopping, App, Smart and Local campaigns, up to a limit of 1,000 per account. Use this level for absolute universals only: careers terms, adult terms, anything that is never relevant to your business under any circumstance.
Shared negative keyword lists sit at campaign level and are the right home for themed groups. A "job seekers" list and a "free and DIY" list, applied to the campaigns that need them.
Campaign and ad group negatives handle everything specific, including the unglamorous job of stopping your own ad groups cannibalising each other. If you run separate ad groups for "leather sofas" and "fabric sofas", each needs the other excluded, or Google will decide for you which one serves.
The mistake worth avoiding
Over-blocking is real, and it is quieter than overspending. Every negative you add narrows the auctions your campaign can enter, and in a Smart Bidding account that also narrows the data the algorithm learns from. Accounts that have passed through several agencies often carry thousands of exclusions nobody can account for, and the campaign can barely spend its budget.
Two rules keep this in check. Add a negative because you saw the term in your own report, not because it appeared on someone's list. And review the list quarterly. If you cannot explain why a term is there, take it out and watch what happens.
How often to do this
Weekly for new accounts and anything running broad match. Monthly once performance is stable. It takes twenty minutes, and it is the highest-return twenty minutes in most Google Ads accounts.
One caveat worth stating plainly. Negative keywords fix who arrives, not what happens after they land. If your search terms look clean and your cost per lead is still bad, the problem has moved down the funnel to your landing page, and no amount of exclusion work will rescue it. That is a conversion rate optimisation job. Be honest with yourself about which of the two problems you actually have, because they need different fixes. Most of our case studies involve both.
If your search terms report has not been opened in months, that is where we would start too. Get in touch and we will tell you what you are paying for.
