If you set up a Google Ads campaign without touching keyword match types, you're running broad match. That's Google's default. And it's likely the reason your cost per acquisition is higher than it should be. This blog post explains why broad match is eating your budget — and the fix is simpler than you think.
Broad match doesn't just show your ad for your target keyword. It shows your ad for searches Google decides are "related." That includes synonyms, implied intent, tangentially connected queries, and sometimes searches that share nothing with your keyword except a word or two.
Here's the part that actually stings. In account management experience, a keyword like "project management software" on broad match can show for: "how to manage a team," "Microsoft Project download," "free task list app," "team productivity tips." Four completely different searches. Four completely different buyers. The spend goes to all of them.
And every one of those irrelevant clicks that doesn't convert gets logged in your conversion history. You're training the algorithm with bad data, and the algorithm uses that data to decide who sees your ads next. It's not just wasted spend — it's compounding damage.
Google's Smart Bidding doesn't fix this. Smart Bidding optimizes for conversions within whatever traffic you're feeding it. If 60% of that traffic is irrelevant queries, Smart Bidding learns from irrelevant signals. You get a well-calibrated system pointed at the wrong audience.
A note on BMM: Broad Match Modified, the +keyword syntax that used to let you anchor specific words, was deprecated by Google in 2021. It now behaves like phrase match with less predictable expansion. If you're still using it, you're not getting the control you think you are.
Search terms audits across practitioner accounts consistently show 30 to 60 percent of spend going to queries with no connection to the original intent when broad match runs unchecked. (This is a practitioner-observed range from account reviews, not a published study; the figure reflects patterns seen in accounts running broad match without negative keyword coverage.) That's not a small leak. That's a structural problem.
What to do instead:
Audit your search terms report weekly. Filter for queries with $50 or more in spend and zero conversions over the last 30 days as a starting threshold — adjust the spend floor to roughly your target CPA. That list tells you exactly where broad match is burning money right now.
Move your high-value terms to phrase or exact match. Exact match for brand and high-intent commercial terms. Phrase match for broader intent where word order matters.
Build a negative keyword list from your search terms report. Every irrelevant query you add as a negative stops that spend permanently.
If you're keeping broad match in your mix, pair it with Smart Bidding and solid conversion tracking. The combination can work when you have enough conversion volume. But broad match plus manual CPC plus no negatives is the worst possible setup. Avoid it entirely.
Start by auditing your own account with the free Keyword Planner Tools keyword audit to see which match types are costing you most. For a full breakdown of when to use each match type and how to structure your keyword architecture without leaks, read the Match Type Coverage guide. Related: Keyword Cannibalization and Negative Keyword Gaps. Most accounts can cut wasted spend significantly just by making these changes — no new campaigns, no new budget required.