The single biggest lever in most Google Ads accounts
Most conversations about improving Google Ads performance focus on the wrong things. People want to talk about ad copy, bidding strategies, smart bidding, audience signals, fancier landing pages. All of those matter. But the single change that produces the biggest improvement in the accounts we audit is much simpler than any of that.
It is a proper negative keyword list.
Negative keywords are the searches you tell Google not to show your ads for. They are the unsexy, unglamorous half of keyword management, and they are the difference between a campaign that performs and one that quietly leaks budget month after month. Here is what they are, why they matter so much, and how to actually build a list that does the work.
What a negative keyword is, in plain English
When you set up a campaign, you tell Google the keywords you want your ads to appear for. What most people do not realise is that Google will also show your ads for thousands of related searches you never typed in, especially if you are using broad match or phrase match keywords.
A negative keyword is the reverse. It is a word or phrase you tell Google to specifically exclude. If you add "free" as a negative keyword, your ads will not appear for any search containing the word "free." If you add "[diy plumbing]" as an exact-match negative, your ads will not appear for that specific search.
That sounds obvious. The reason it matters is that most accounts have no real negative keyword list at all. They might have a handful of obvious exclusions added years ago and forgotten. Meanwhile their budget is being drained on searches that have nothing to do with the business.
What this looks like in practice
We audited an account last month for a Cheltenham building firm. They were spending about £1,800 a month on Google Ads with a vague sense that the leads were not great. We pulled their search terms report for the last 90 days and went through it line by line.
In that report we found their ads had been shown for searches including:
- "building apprenticeship cheltenham"
- "how to lay bricks"
- "average builder salary uk"
- "self build courses"
- "B&Q timber prices"
- "free building quotes"
None of those people were ever going to hire a building firm. They were either looking for work, doing the job themselves or shopping around for free quotes from anyone who would offer one. Between them they had consumed roughly 22 percent of the account's budget over three months.
A properly built negative keyword list would have prevented every one of those clicks. Twenty-two percent of the budget reclaimed and redirected at people who actually wanted to hire a builder.
This is not unusual. It is the rule. Almost every account we audit has the same pattern.
Why this happens by default
The reason negative keywords matter so much is that Google's match types have grown progressively looser over the years. In particular, broad match, Google's default match type, now shows your ads for an enormous range of searches that bear only a passing resemblance to your original keyword.
When you add "kitchen designer Cheltenham" on broad match, Google might decide to show your ad for "kitchen designer jobs," "kitchen designer salary," "kitchen designer apprenticeship" and "kitchen designer training." It will also show your ad for "free kitchen design software" and "diy kitchen design." All of those clicks cost real money. None of them will become customers.
Google does this because, statistically, broad match generates more clicks and more revenue for Google. It is not designed to protect your budget. That is your job. The negative keyword list is the tool you use to do it.
How to build a useful negative keyword list
The shortcut is to dump in a generic list you found online. That helps a little. The real value comes from building a list tailored to your specific business, and the only way to do that is to look at the actual searches your ads have been shown for.
Here is the process we run on every new account.
Step one: pull the search terms report
In the Google Ads interface, go to Insights and Reports, then Search Terms. Set the date range to the last 90 days and export everything. Open it in a spreadsheet so you can sort and filter.
This report shows you every search query your ads have actually appeared for. It is the single most important document in any Google Ads account, and most account managers never look at it.
Step two: read every line
There is no clever shortcut here. You have to read the searches. As you go through, you are looking for three categories of waste:
-
Searches with no commercial intent. People researching, learning, looking for free advice. "How to," "diy," "tutorial," "course," "training," "guide," "free."
-
Searches in adjacent industries that are not yours. A kitchen designer's ads showing for "kitchen porter jobs." A solicitor's ads showing for "free legal advice." A plumber's ads showing for "plumbing apprenticeship."
-
Searches for things you do not offer. A residential builder's ads appearing for "commercial building." A wedding photographer's ads showing for "passport photos."
Every one of these is a candidate for the negative list.
Step three: categorise your negatives
Some negative keywords belong at the account level. They apply to everything you sell. Words like "jobs," "salary," "career," "apprenticeship," "courses" and "free" almost always belong here, because no business that earns its living wants to show ads for those terms.
Other negatives belong at the campaign or ad group level. A campaign for residential kitchen installs might exclude "commercial," while a separate campaign aimed at commercial kitchens would not. Adding it at the account level would block the wrong campaign.
Keep the lists organised. We use shared negative lists in Google Ads to make this easy to maintain across multiple accounts and campaigns.
Step four: do this every month
Search behaviour changes constantly. New phrases appear. Old terms shift in meaning. People search differently in summer than they do in winter. Your negative list is never finished.
We review search terms on every client account at least monthly. New negatives go in. Performance improves. The cycle repeats.
What this is worth, in money
For most local service businesses spending £500 to £2,000 a month on Google Ads, a properly maintained negative keyword list saves between 15 and 30 percent of the monthly budget. That money does not disappear. It gets redirected, automatically, to the searches that do convert.
A business spending £1,000 a month and reclaiming 25 percent of wasted spend is effectively getting £250 worth of high-quality clicks they were not getting before. Over a year, that is £3,000 of better targeted budget without spending an extra penny on ads.
This is why negative keywords are the first thing we look at when we audit an account. Not because they are interesting, but because they are nearly always the biggest single lever in the account.
What to do today
If you run your own Google Ads account, the most valuable hour you can spend this week is pulling your search terms report and reading it. Not skimming, reading. Highlight every search that is not a real customer for you. Add the patterns you spot to a negative keyword list. Do it again in 30 days.
If you would rather not do this yourself, and most people would not, a free Google Ads audit from us will give you a full breakdown of where your budget is currently being wasted and exactly what we would change. The negative keyword opportunity is usually the largest single saving on offer.