How negative match types work
A negative keyword tells Google Ads which searches must not trigger your ad. Like a positive keyword it carries a match type — broad, phrase or exact — and although the labels are identical, the behaviour is not. Confusing the two is where most of the money leaks out of a Search account.
A negative broad keyword blocks a search only when every word in the negative appears in it, in any order. A negative phrase blocks a search that contains those words together in that order, with anything either side. A negative exact blocks only a search that matches word for word, with nothing added.
The difference that catches people out is that negatives are read literally. Your positive keywords are stretched to close variants — plurals, misspellings, abbreviations and, on broad match, related meanings. Negatives are not stretched in the same way, so blocking one spelling leaves the rest running. Treat a negative as a filter on the words you typed, not on the idea behind them.
Why negative match types matter
Picking the wrong type produces one of two failures, and they look nothing alike in a report. Too narrow, and the waste carries on: an exact negative for one unwanted query does nothing about the many near-identical queries around it. Too wide, and you quietly amputate demand — a broad negative built from a common word can block searches that were about to convert, and the loss never appears as a line item because the impressions simply stop.
The stakes rose with broad match and automated bidding, which are designed to reach beyond your keyword list. The wider the matching, the more your negatives, and the match types you give them, are the only thing holding the shape of the campaign.
Common mistakes with negative match types
The commonest is treating a negative broad keyword as a theme blocker. Several common words entered as one broad negative block only searches containing all of them, which is far narrower than people expect. A single common word entered as a broad negative is far wider than they expect, and a block on free will happily stop free delivery for a shop that charges for its goods.
Two others are worth naming. Plurals and misspellings need their own entries, so blocking one form and assuming the family is covered leaves the rest live. And a negative added at ad group level can collide with a keyword in that same ad group, leaving the keyword eligible on paper but never serving; the conflicts view in Google Ads is where that surfaces.
How to act on it
Work from evidence rather than imagination. Open the search terms report, sort by cost, and decide term by term. As a working rule, use phrase negatives for themes you never want — job seekers, DIY instructions, a competitor’s brand — and exact negatives when one specific query is expensive while its neighbours are fine. Save broad negatives for cases where the combination of words is genuinely disqualifying.
Anything that applies account-wide belongs in a shared negative keyword list, so it is maintained in one place, while campaign-specific blocks stay at campaign level. If you are running Google Search campaigns on broad match, review the report on a fixed schedule rather than when something looks wrong — by then the money has already gone.