Broad match modifier exists on Amazon — in one campaign type, and probably not the one you are using.

Broad match modifier is two different things with one name, and almost every guide written about it is answering the wrong one. On Google Ads it was a syntax that no longer exists. On Amazon Ads it is a live feature that exists in exactly one place — Sponsored Brands — and not in the campaign type most sellers are actually asking about. If you have been typing a plus sign in front of Sponsored Products keywords, nothing has been enforcing it.

The Google version, and why it is gone

Broad match modifier was a Google Ads notation. You wrote +running +shoes and Google promised that both words, or close variants of them, would appear in any query it matched you to — in any order, with anything else around them. It was the middle setting between broad match, which could drift anywhere, and phrase match, which insisted on word order.

Google folded it away in 2021. From February of that year phrase match began absorbing the modifier's behaviour, and from July advertisers could no longer create BMM keywords at all; existing ones kept serving but behaved as phrase. So on Google the answer to "how do I use broad match modifier" is that you do not, and have not been able to for five years.

That matters here because a large share of the advice ranking for this term is Google advice with the word "Amazon" pasted over it. The mechanisms are not the same, and the substitution Google made — modifier behaviour into phrase — is not the substitution Amazon made.

The Amazon version, which is alive and narrower than you think

Amazon does document a broad match modifier. Its own keyword targeting guidance describes adding a plus symbol in front of a word so that the word must appear in the shopper's query: the keyword +kids shoes can match "kids sneakers" or "running shoes for kids", but cannot match "sneakers" or "running shoes". That is the same idea Google retired, still working.

The catch is the campaign type. Amazon documents the modifier under Sponsored Brands. It is not part of the documented Sponsored Products keyword syntax — and Sponsored Products is where the overwhelming majority of seller spend sits. A plus sign there does not throw an error. It is simply not a promise anyone made you.

This is worse than an unavailable feature, because a silent no-op looks exactly like a working one. The campaign builds, the keyword shows as eligible, impressions arrive. Nothing tells you the constraint is not being applied. The only place it shows up is the search-term report, weeks later, as queries that do not contain the word you thought you had required.

What Sponsored Products gives you instead

Sponsored Products has three widths and no modifier. Broad, phrase and exact are a control dial rather than a quality ladder: broad reaches queries related to your keyword in any order, phrase requires your words in the order you wrote them with anything before or after, exact requires the keyword itself or a close variant.

Read those definitions next to what the modifier did and the gap is specific. The modifier let you say "these particular words must be present, in any order." Amazon's phrase match says "these words must be present, in this order." Broad says "something like this." There is no setting for the middle case, which is exactly the case people come looking for.

Getting the constraint back without the syntax

The honest substitute is a pair, not a setting: phrase match for the part you want guaranteed, and a negative list for the drift you want removed.

Suppose you sell a stainless steel dog bowl and the word that must never fall out of the query is "dog". On Google you would have written +dog +bowl. On Amazon Sponsored Products you run dog bowl as phrase, which holds the pair together in order, and you run dog bowl as broad at a lower bid to see what the semantic engine brings back. Then you read the search-term report and negate the seams that have nothing to do with dogs — "cat bowl", "cereal bowl", "bowl set" — as negative phrase, which kills a family of queries rather than one query at a time.

That is more work than a plus sign, and it is also strictly more powerful, because the negative list is the part that keeps improving. A modifier only enforces what you already knew to require. A negative list learns the ways your category goes wrong, which is the half you cannot predict when you build the campaign.

The number that decides whether any of this was worth doing

Match width and modifiers govern who is eligible to cost you money. They do not price a click. A broad keyword bid below break-even is safer than a perfectly constrained one bid above it, and no amount of syntax rescues a bid that was never economic.

Break-even ACoS is your margin after COGS and fees. A product carrying 35% margin breaks even at a 35% ACoS — about a 2.9x ROAS. Every question about match type is downstream of that line: the width decides which shoppers reach the auction, the bid decides whether their click was worth winning.

Where this gets more expensive in Europe

Broad match leans on Amazon's understanding of shopper intent, and that understanding is not equally developed in every language. A broad keyword that behaves itself on amazon.co.uk can sprawl on amazon.it, where there is less data behind the semantic match. So the width you would have constrained with a modifier is the width that varies most across marketplaces.

The practical consequence is that the phrase-plus-negatives substitute has to be built per marketplace, in each language, against each market's own search-term report. A negative list translated from your German account is not a negative list for your Italian one — the wasteful queries are different words describing different mistakes.

The one-line version

Broad match modifier is a Sponsored Brands feature on Amazon and a retired Google feature everywhere else. In Sponsored Products it does not exist, a plus sign is silently ignored, and the way to get the constraint you wanted is phrase match for the words that must hold plus a negative list for the drift you did not predict.

Common questions

Does Amazon have a broad match modifier?

Yes, but only in Sponsored Brands. Amazon documents the "+" prefix as a Sponsored Brands feature: "+kids shoes" matches only queries that contain the word "kids". It is not part of the documented Sponsored Products keyword syntax, so typing a plus sign in front of a Sponsored Products keyword does not buy you that guarantee.

Is broad match modifier the same on Amazon as it was on Google Ads?

No. Google retired its broad match modifier: from February 2021 phrase match absorbed the behaviour, and from July 2021 no new BMM keywords could be created. Amazon never adopted Google’s syntax wholesale, and the Sponsored Brands modifier that does exist is a narrower tool than Google’s was.

What do I use instead in Sponsored Products?

Phrase match plus a maintained negative list. Phrase requires your words in order, which is a stricter promise than "these words must appear somewhere"; negatives remove the query families you never wanted. The pair gets you most of what the modifier was for, and unlike the modifier it also works on the discovery you have not thought of yet.

Will a plus sign break my Sponsored Products keyword?

It will not error, which is the problem. The keyword is accepted and runs as ordinary broad match, so the campaign looks fine and the constraint you thought you set is not being enforced. Check the search-term report rather than the keyword list: if queries are appearing without your required word, the modifier is not doing anything.

If you want to know whether a plus sign has been quietly doing nothing in your account, we will read the search-term reports and tell you. No card, and you keep the findings either way.