Negative keywords in Google Ads — and the close-variants trap
Negative keywords are the cheapest optimisation lever in Google Ads — they cost nothing and take effect immediately. They just do not work the way most people assume, and that gap is where quiet wasted spend lives.
What they are for
"Negative keywords let you exclude search terms from your campaigns and help you focus on only the keywords that matter to your customers." (Google Ads Help)
The close-variants trap
For normal keywords, Google automatically includes misspellings, singular/plural and similar forms. For negative keywords it does not — For negative keywords it does not: "Negative keywords won't match to close variants or other expansions." Google's own example: excluding the broad match negative for flowers stops the ad on a search for red flowers, but not on red flower. (Google Ads Help)
That is the single most important line on this page. In practice:
| You exclude | Blocked | Still runs |
|---|---|---|
| free | free | freebie, no cost, gratis |
| jobs | jobs | job, vacancy, careers, hiring |
| flowers | red flowers | red flower |
Add the base form only, consider the job done, and you keep paying for every variant. Each exclusion needs its word forms and the obvious synonyms alongside it.
The 16-word limit
A detail almost nobody mentions: "Your ad might still show when someone searches for a phrase that's longer than 16 words, and your negative keyword follows that 16th word." (Google Ads Help)
Why it matters now: with long spoken or AI-style queries, an exclusion can simply miss. One more reason to review exclusions against real search terms rather than building a list once and forgetting it.
Where exclusions should come from
Not from guesswork — from the search terms report, which shows what you actually paid for. How to read it and turn it into exclusions is in the search terms report guide.
What exclusions cannot do
They make traffic cleaner, not bigger. If a campaign is not serving at all, negatives are not the cause — see no impressions. And if clicks arrive but nobody enquires, look at the ad and landing page — see no clicks.