How do you stop broad match burning your budget?

Broad match is the setting most likely to be quietly spending your Google Ads budget on people who were never going to become customers. It isn't a bad setting. It's a powerful one that Google now switches on by default, and it only behaves when the rest of your account gives it good reasons to.

This guide covers what broad match actually does today, where it wastes money in a small or mid-sized account, and the seven controls that stop it. You don't need to abandon broad match to fix it. You need to decide what it's allowed to spend and what it's allowed to learn from.

What broad match actually does in Google Ads today

Google's own page on keyword matching options in Google Ads says a broad match keyword can show your ad on searches related to it, including searches that don't contain the direct meaning of your keyword. To decide what's related, it can also take into account the searcher's recent search activity, the content of your landing pages and assets, and the other keywords in the same ad group.

Three details on that page matter more than the definition:

• Broad match is the default. Every keyword you add is broad match unless you tell Google otherwise.
• Broader match types capture everything narrower ones do, plus more. A broad keyword can match every search its phrase and exact versions would, then keep going.
• Google says it's critical to use Smart Bidding with broad match, because every search is different and the bid for each one should reflect what's known at auction time.

That last point is the whole story in one line. Broad match hands Google a much bigger pool of searches, and Smart Bidding is what's supposed to decide which of them are worth paying for. If Smart Bidding doesn't have good data to decide with, the bigger pool is just a bigger bill.

Why broad match now carries most of the spend

Advertisers have moved with Google. Optmyzr's 2026 study of 30,000 Google Ads accounts, using February 2026 data, found exact match's share of spend fell by nearly 10 percentage points between 2022 and 2026, while broad match climbed to become the largest match type by budget. The same study found exact match still led on efficiency across non-branded campaigns, and that broad match "generates significantly more volume, but that volume comes at a cost".

So the market has shifted its money towards broad match faster than the performance case has shifted with it. That gap is where budgets burn.

Where broad match burns budget in a lead generation account

The waste usually comes from three places. None of them is a Google error. Each is broad match doing exactly what it was told, with the wrong instructions.

Searches Google considers related that your customers wouldn't

To show what "related" looks like in practice, we pulled the keyword ideas Google Ads returns for the single word "plumber" in Australia on 1 October 2026, using Google's own keyword data through DataForSEO's keyword data API. It came back with 673 ideas that have search volume, adding up to 332,930 searches a month.

Most of them are people who want a plumber. Plenty aren't:

The Reece search is the one to sit with. It has the same volume as "plumber", it's about 12% of all the searches in that list, its average cost per click in the same data is about 4% of what "plumber" costs, and nobody searching it needs a plumbing business. Google's keyword tool itself tags 116 of the 673 ideas as other brands. If Google's own keyword tool treats a search as related to your keyword, it's safest to assume broad match can reach it too, and a negative keyword is the only thing that tells it not to.

Thin conversion data that Smart Bidding can't learn from

Smart Bidding needs conversions to learn which searches are worth paying for. Google's Smart Bidding overview notes that some strategies rely on a minimum volume of historical conversion data for best results. A small lead generation account might record a handful of enquiries a week, which is a thin signal for sorting thousands of loosely related searches.

Optmyzr's 2026 data points the same way. In lead generation accounts, the ones without revenue tracking, broad match "loses its footing more noticeably" than in ecommerce, because the algorithm has less to work with. Its earlier study of 2,637 accounts, using Q1 2023 data, found 70.79% of accounts had a better cost per acquisition on exact match than on broad match, and 85.65% had a better click-through rate.

Conversions that were never real leads

The third leak is quieter. If your conversion action counts a page view, a click on a phone number or a spam form fill, Smart Bidding learns to find more of those. Broad match then goes looking for the kind of searcher who produces them. That's how an account can report a falling cost per conversion while the phone rings less, and it's the same pattern behind why cheap leads so often turn out to be bad ones.

How to stop broad match burning your budget

These controls are in the order we'd apply them. The first three cost nothing but time, and they're where most of the waste is usually stopped.

1. Decide what a lead is worth before you broaden anything

Broad match without a target is an open cheque. Before you let it run, work out the most a lead can cost and still make you money, and set a target cost per acquisition near that number. Then make sure the conversion you're optimising for is a genuine enquiry: a submitted form that reached your inbox, or a call over a sensible length. Everything else can stay in the account as a secondary conversion that's reported but not bid on.

2. Start with phrase and exact, and let broad match earn its place

Phrase match is the under-rated middle option. In Optmyzr's 2026 lead generation data it held the largest share of both spend and conversions, and across non-branded campaigns it "consistently punches above its weight on conversions". For a new or low-volume account, a sensible default is:

• Exact match for the handful of searches you know convert, such as your core service plus "near me".
• Phrase match as the day-to-day workhorse.
• Broad match added later, once the account records enough genuine conversions for Smart Bidding to tell good searches from bad.

3. Build negative keyword lists before you launch

Negative keywords are how you draw the edges broad match can't see. Google's rules for how negative keywords behave are stricter than most people expect: negatives don't match close variants or other expansions, so you need to add synonyms and singular or plural versions yourself. Casing and misspellings are handled for you.

Google also lets you create up to 20 shared negative keyword lists per account, each holding up to 5,000 negatives. We'd build three before launch:

1. Jobs and training: salary, jobs, apprenticeship, course, careers.
2. DIY and supplies: how to, parts, pipe, fittings, and the names of the retailers people shop at.
3. Services you don't offer: the work you turn down, and the suburbs or regions you don't cover.

4. Read the search terms report while the account is young

The search terms report shows the actual searches your ads appeared on, and it's where new negatives come from. Read it often in the first weeks of any broad match campaign. Two things to know: Google omits search terms without enough query activity for privacy reasons, so the report never shows everything, and its match type column tells you how closely each search relates to your keyword. The searches you can't see are one more reason to keep broad match on a budget you can afford to lose while it learns.

5. Use brand exclusions instead of chasing brand negatives

Searches for other businesses' names are a common broad match leak, and adding every competitor and supplier as a negative, spelling by spelling, never ends. Google's brand settings for Search and Performance Max let you exclude a brand from a campaign, and Google says brand lists match the brand across multiple languages without you entering each spelling or variant. For a local business, excluding the big suppliers and franchise names in your category is usually a faster fix than a growing negative list.

6. Give broad match its own budget

If broad and exact keywords share one campaign budget, broad match can spend it before your best searches get a look in. Google's page on bids and budgets explains that a campaign can spend up to 2 times its average daily budget on a single day, although over a billing period you're never charged more than 30.4 times the daily amount. Put your proven exact and phrase keywords in their own campaign with a protected budget, and test broad match in a separate one with a budget you've chosen deliberately. Our Google Ads budget calculator helps you size both.

7. Check your campaigns after the AI Max upgrade

This one is new. Google's announcement on upgrading campaigns to AI Max, updated on 11 June 2026, says Search campaigns using the campaign-level broad match setting will continue to be upgraded to AI Max automatically from September 2026. AI Max's search term matching uses broad match and keywordless technology to reach searches beyond your keywords. If you had that setting on, open the campaign, confirm what's now switched on, and check the search terms report again. Your negatives and brand exclusions still apply, and they matter more once matching widens.

Broad, phrase and exact match compared

The definitions in the second column come from Google's keyword matching page. The rest is our judgement, and your mix will depend on how many genuine conversions your account records.

When broad match is worth running

Broad match earns its keep when the account can feed it. Google's AI Max announcement reported that advertisers switching on AI Max typically saw 14% more conversions or conversion value at a similar cost per acquisition or return on ad spend, and 27% for campaigns still mostly on exact and phrase keywords, based on Google's internal data for non-retail advertisers. That's the upside, and it's real when the conditions are right. Before you switch it on, check you can say yes to all of these:

• Your main conversion is a genuine lead, not a page view or a click.
• The account records conversions steadily, week in, week out.
• Smart Bidding has a target that reflects what a lead is worth to you.
• Negative lists and brand exclusions are in place before launch.
• Broad match has its own budget, separate from your proven keywords.
• Someone reads the search terms report and acts on it.

If you can't tick all six, broad match will probably cost you more than it finds. Performance Max has the same weakness for the same reason, and why Performance Max leaks spend when nobody steers it walks through the overlap.

This is the work our Google Ads management that starts with match types and negative lists is built around, whether that's for a tradie chasing jobs in Google Ads campaigns in Adelaide or a clinic on the Gold Coast. As a growth marketing agency for businesses that pay for every click, we'd rather tighten the account you already have than tell you to spend more on it.