Query fan-out

Definition

Google defines query fan-out as “a set of concurrent, related queries generated by the model to request more information and fetch additional relevant search results to address the user’s query.” Its example: for “how to fix a lawn that’s full of weeds”, fan-out queries might include “best herbicides for lawns”, “remove weeds without chemicals” and “how to prevent weeds in lawn”.

Officially documented · Google Search Central

Both AI Overviews and AI Mode “may use” query fan-out. It issues related searches across subtopics and data sources. Google says this lets it show a wider and more diverse set of supporting links than a classic web search.

Officially documented · Google Search Central

What it implies for a site

A page can be cited for a sub-question the user never typed. Covering a topic’s sub-questions in genuinely useful pages therefore matters more than matching the original query string.

What not to do

Google’s scaled content abuse spam policy covers separate content for every possible variation of how people might search, including fan-out queries. Creating it primarily to manipulate rankings or generative AI responses is a violation. Google also calls it “an ineffective long-term strategy”.

Officially documented · Google Search Central

What has been measured

A University of Toronto study (October 2026) replayed its questions through the engines’ APIs. Every page ChatGPT cited was one its own search had retrieved, and that search used sub-queries the model rewrites on every answer. For all of an answer’s queries, 97% of the pages ChatGPT retrieved were absent from Google’s top 50 and 99% from Bing’s top 30, as were 93% of the pages Gemini cited, although Gemini is grounded on Google Search. The websites of 51% of ChatGPT’s pages did appear in Google’s top 50, so the engines often pick different pages from the same websites.

Research-backed · Chen and Koudas (University of Toronto), arXiv:2610.15033

This is one study of two markets. It describes ChatGPT and Gemini, not Google’s own fan-out.

Not established

• Which fan-out queries Google generates for a given query. Google does not publish them, and they are not reported in Search Console.
• Whether other AI search products document a comparable technique. Their documentation does not describe one in these terms, though the study above observed ChatGPT rewriting each question into new sub-queries.

Related

• Google AI Overviews — where fan-out is used.
• Generative Engine Optimization (GEO) — the broader practice.