AI Max for Online Stores: What It Does and Why I Keep It Off

AI Max is Google’s add-on for Search campaigns that widens which searches your ads match, rewrites your ad text and can change the landing page. I ran it in 6 online store accounts, and it hurt performance in all 6. On mature accounts, most of the search terms it brought in had zero conversions.

This guide explains what AI Max does and what Google claims for it. It also covers what I saw in store accounts, and which settings to check now that Google upgrades campaigns automatically.

What is AI Max for Search campaigns?

AI Max for Search campaigns is a set of three features you switch on in a Search campaign (Google Ads Help):

Feature	What it does
Search term matching	Finds searches beyond your keywords, using broad match and “keywordless” matching based on your ads and landing pages
Text customization	Writes new headlines and descriptions for each search
Final URL expansion	Sends people to the page on your site that Google thinks fits the search best

You keep some controls: brand inclusions and exclusions, URL controls, and locations of interest, at campaign or ad group level. Google recommends conversion or conversion value bidding with AI Max and advises against manual CPC.

Since 30 April 2026, there is also AI Max for Shopping campaigns. It adds text customization, final URL expansion and “optimal format selection”, which picks a text ad or a Shopping ad for each search. Final URL expansion can be turned off there (PPC Land).

What does Google claim AI Max delivers?

Google’s main claim is 14% more conversions or conversion value at a similar CPA or ROAS. The footnote on Google’s help page says this comes from “Google internal data, 2025; for non-Retail advertisers” (Google Ads Help).

That footnote matters for anyone running an online store. Retail is the category the figure leaves out.

Google has published other numbers since, as collected by PPC Land:

• 7% more conversions when all features are used, compared with search term matching alone (April 2026). PPC Land notes this figure also excluded retail.
• 27% more conversions at a similar CPA or ROAS for campaigns built mostly on exact and phrase match (May 2026).
• 15% more conversions or value at a similar ROAS, said on Alphabet’s earnings call on 22 July 2026.

All of these come from Google. I haven’t found Google figures for online stores specifically.

What happens when online stores turn on AI Max?

In my accounts, it lowered performance. I ran AI Max in 6 online store accounts, and it hurt performance in every one of them.

What I saw:

• AI Max’s share of search terms varied a lot, from a few percent to 50%, depending on the account.
• On mature accounts, most AI Max search terms had zero conversions. These accounts already had keywords and Shopping campaigns covering the searches that sell.
• On new accounts, AI Max did catch some good search terms, because there were fewer keywords covering them yet.

Independent retail data points the same way. Smarter Ecommerce (smec) found that across more than 250 retail campaigns, AI Max conversions came at about 35% lower ROAS than traditional match types in the same campaigns (PPC Land).

Why does AI Max do worse on mature store accounts?

My explanation, based on what I saw in those 6 accounts: a mature store account has already found most of the searches that sell. Bestsellers sit in exact match, Shopping covers product searches, and negative keywords block the rest. What’s left for AI Max to find is mostly searches that were left out for a reason.

A new account hasn’t done that work yet. There, AI Max can still find searches that sell, because nobody has added them as keywords.

AI Max also changes how existing keywords behave. Smec looked at 383 million impressions from ecommerce Search campaigns with AI Max in EMEA, from January 2025 to July 2026. By July 2026, more than a quarter of the impressions attributed to exact match keywords came through AI Max search term matching instead of a literal exact match (PPC Land).

What changed with AI Max in 2026?

Google is moving campaigns to AI Max whether or not you choose it (PPC Land):

Campaigns using	Automatic upgrade
Automatically created assets	From September 2026
The campaign-level broad match setting	From September 2026
Dynamic Search Ads (DSA)	February 2027, moved from September 2026

Creating new DSA campaigns stops again in January 2027, according to the Google Ads Developer Blog announcement of 11 June 2026.

The upgrade doesn’t switch on every feature for everyone. According to Google, upgraded DSA campaigns get all three features. Campaigns with automatically created assets get search term matching and text customization, and campaigns with the broad match setting get search term matching only (Google).

One change affects keywords directly. Google’s help documents now say that broad keywords lose a privilege when you turn off the campaign-level broad match setting or move to AI Max: they’re no longer treated as exact match keywords in prioritization. To keep that behaviour, Google suggests adding exact match copies of those keywords (Search Engine Roundtable).

How do you limit the damage if you test AI Max?

Test it in a controlled way, and judge it against your break-even ROAS:

1. Run it as an experiment, on one campaign, with a control campaign left unchanged.
2. Add brand exclusions, so AI Max doesn’t take credit for searches for your own store name. The brand search guide explains why that matters.
3. Set URL controls, or turn off final URL expansion, so people don’t land on blog posts or category pages you didn’t choose.
4. Keep exact match copies of your bestseller keywords, so they keep their priority.
5. Check the search terms report weekly, filtered to AI Max, and add negative keywords for terms that spend without converting.
6. Compare total results, including the campaign’s existing keywords. Smec’s data shows AI Max can take impressions from your exact match keywords.

When can AI Max make sense for an online store?

On a new account with little keyword data. That’s the only situation where I saw AI Max find good search terms that the keywords didn’t already cover.

If you use it there, treat it as a way to find keywords. When AI Max finds a search term that sells, add it as a keyword, and keep watching the AI Max share.

On a mature store account, my answer is to keep it off, and to check that the September 2026 upgrades haven’t switched it on without you noticing.