GEO glossary

Query fan-out

Query fan-out is the technique AI search systems use to split one question into several related sub-queries, run those searches in parallel and combine the results into a single answer. Google says AI Mode and AI Overviews may use it, and other AI assistants retrieve pages in a similar way.

Reviewed by Gareth Hoyle, Managing Director
Last reviewed 31 October 2026

How does Google describe query fan-out?

When Google announced AI Mode on 5 March 2025, it said the system issues multiple related searches concurrently across subtopics and multiple data sources, then brings the results together. In May 2025 it described AI Mode as breaking a question into subtopics and issuing a multitude of queries simultaneously on the user's behalf. Deep Search takes this further and can issue hundreds of searches for one report.

Google's Search Central documentation says both AI Overviews and AI Mode may use query fan-out to build a response.

Why it matters for SEO

Fan-out means the cited page may never rank for the words the user typed. It only needs to be retrieved for one of the sub-queries. Ahrefs found that only 12% of URLs cited by AI assistants ranked in Google's top 10 for the original prompt, and noted that assistants may never search the exact prompt at all.

It also changes what a strong page looks like. A page that answers the main question and its follow-ups, such as cost, comparisons, eligibility and timescale, can be picked up by more of the fanned-out searches.

How to plan content for it

Start from the decision the user is trying to make, then work backwards to the questions they need answered.

List the sub-questions a buyer asks before deciding
Give each sub-question its own heading and a direct answer
Use specific figures, names and dates that a sub-query can match
Check which sub-topics competitors cover that you do not

Example

Someone asks AI Mode whether a heat pump is worth it for a 1930s semi in Yorkshire. The system might search for heat pump running costs, insulation in older houses, the Boiler Upgrade Scheme grant and installers in Yorkshire, then combine the results. An installer guide that covers all four has four chances to be retrieved.