What is query fan-out?
Also known as fan-out queries, query fanout, sub-queries
Definition
Query fan-out is when an AI search system splits one question into many related searches, runs them at the same time and combines what it finds into a single answer. Google uses it in AI Mode.
Key points
- Query fan-out turns one question into many hidden searches on subtopics.
- Google says AI Mode uses it, and that AI Overviews may use it too.
- It rewards pages that cover a topic well and answer follow-up questions clearly.
What does it mean in practice?
Someone asks for the best electric car for a family of five with a long commute. An AI system with query fan-out might search separately for seven-seat electric cars, real-world range, boot space, charging times and running costs. It reads the results for each and then writes one answer.
Google says AI Mode uses this query fan-out technique, breaking a question into subtopics and issuing many queries at once. Its guidance on AI features says AI Overviews may use it too.
Why does it matter for AI search?
Fan-out means your page can be pulled into an answer for a question it never targeted. A car dealer's page on charging costs could be cited in an answer about family cars, because it answers one of the hidden sub-questions well.
It also means covering a topic well beats chasing one keyword. It helps to think about the follow-up questions a buyer would have and answer each clearly. Prompt research can surface those related questions from People Also Ask, autocomplete and Reddit. Our Google AI Mode guide explains how fan-out shapes results there.
Related terms
These terms connect to query fan-out.
- AI Mode, the Google experience built around fan-out.
- AI Overviews, which Google says may also use it.
- Retrieval-augmented generation, the look-up step fan-out widens.
- People Also Ask, a useful clue to likely sub-questions.
Common questions
Can I see the fan-out queries Google runs?
How do I optimise for query fan-out?
Related reading
Google AI Mode, what it means for your business
What Google AI Mode is, how query fan-out works, how it differs from AI Overviews, and how to measure it with the Search Console generative AI report.
Prompt and question research
AI prompt research pulls real questions from People Also Ask, autocomplete, Reddit and your own enquiries, then turns them into prompts, tasks and content.
AI Mode
A plain definition of Google AI Mode, how it uses query fan-out, and how to see your AI Mode impressions in Search Console.
Retrieval-augmented generation (RAG)
A plain definition of retrieval-augmented generation (RAG), how AI search engines use it to answer questions, and why it keeps classic SEO relevant.
AI crawler
A plain definition of AI crawlers such as GPTBot and OAI-SearchBot, what each type does, and why blocking one can cost you visibility.
AI Overviews
A plain definition of Google AI Overviews, how pages get cited in them, and why they matter for your search traffic and your everyday visibility online.