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The AI Overview Trigger Index

"AI Overviews appear on about half of searches" is the number everyone repeats — but a single average hides the real driver. Whether Google shows an AI Overview is decided almost entirely by intent. We ran matched prompt sets across five query types and measured how often each one triggered an AI Overview.

Published July 5, 2026 · cloro themed prompt corpus · ~1,900 prompts across six engines

Key findings

98% → 3%

AI Overview trigger rate swings from ~98% on commercial and voice queries to ~3% on local restaurant queries. Intent, not topic, decides whether Google's AI answers.

Local ≈ off

For "restaurants near me"-style intent, Google almost never shows an AI Overview (3%) — it hands the query to the map pack instead. AI search and local search are still largely separate worlds.

Only Google is selective

ChatGPT, Gemini, and Copilot returned an answer on 100% of prompts in every theme — the conversational engines always answer. Google's AI Overview is the one surface that decides whether to appear, which is why "does AI answer this query?" is really a question about Google.

AI Overview trigger rate by intent

Share of prompts in each theme where Google rendered an AI Overview, from matched prompt sets run through cloro's monitoring.

Voice / spoken-style97.8%Commerce / product97.6%Brand / navigational87.5%Travel / destination52.3%Restaurants / local3.0%
Google AI Overview trigger rate by query intent. Matched prompt sets (n = 317 voice, 552 commerce, 400 brand, 258 travel, 400 local).

Has the rate moved? An 18-week trend

Intent decides the level; over time, the blended rate barely moves. Tracking a fixed panel of the most-consistently-monitored Google queries every week, the AI Overview trigger rate has held in the mid-70s for four months — climbing from ~69% in early March to a ~78% peak in May, then easing to ~67% most recently.

60%70%80%
Weekly AI Overview trigger rate on a fixed 80-query monitoring panel (Mar–Jul 2026). A stable mid-70s band, not a step change.

What this means

If you're forecasting AI-search exposure for a set of keywords, the blended "~50%" figure will mislead you in both directions. A commercial-heavy keyword set is almost fully AI-answered (~98%); a local-service set is barely touched (~3%). Score your own query mix by intent before assuming how much of it AI Overviews actually reach.

It also reframes what "AI search optimization" means per surface. On the conversational engines, the answer always renders — the question is whether you are named in it. On Google, the prior question still stands: will an AI Overview appear for this query at all? For commercial and informational intent, plan for yes; for local intent, plan for the map pack.

Methodology

Matched, stratified prompt sets (~1,900 prompts) were run through six AI engines — ChatGPT, Perplexity, Gemini, Copilot, Google AI Overview, and Google AI Mode. "Trigger rate" is the share of a theme's prompts where a given surface returned an answer; the figures above are Google's AI Overview surface. Themes are directional groupings of intent (commercial, voice-style, brand, travel, local dining), not an exhaustive taxonomy — read them as a spread across intent, not precise category boundaries.

Cite this study

cloro. (July 5, 2026). AI Overview Trigger Index: How Query Intent Decides Whether AI Answers. cloro Research. https://cloro.dev/research/ai-overview-trigger-index/

More studies from cloro's monitoring corpus are in the research index.

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