What Triggers AI Overviews? 86 Factors and 146 Million SERPs Analyzed

To answer these questions, we analyzed our database of 146 million SERPs and explored how often AI Overviews appeared for 86 different keyword traits, from YMYL to CPC to query length.

Across our data set, AI Overviews appear for 21% of keywords. But looking at specific keyword categories, some categories have as high as a 60% chance of triggering an AI Overview, and others as low as 1%.

AI Overviews appear on 20.5% of all SERPs (29,991,998 out of 146,122,391).

Put another way, most websites can expect to compete with a Google-branded, AI-generated blog post for 1 in every 5 of the keywords they target.

We can use this rate as a baseline to see whether different keyword characteristics—like intent, length, or CPC—make it more or less likely for AI Overviews to trigger.

Here’s a chart summarising our findings. Query types with a positive difference from the baseline (i.e. bars on the right of the mid-line) are more likely to trigger an AI Overview; those with a negative difference (bars on the left) are less likely to trigger an AI Overview.

99.9% of keywords that trigger AI Overviews are Informational in intent. 5.5% of AIO keywords are considered Commercial, 1.2% Transactional, and just 0.1% Navigational.

Relative to the baseline rate of 20.5%, we can see that AIOs are slightly more likely to appear for Informational keywords, but vastly less likely to appear for other intent types, especially Navigational. Just 0.09% of Navigational keywords trigger an AI Overview:

76.3% of keywords that trigger AIOs are considered non-branded (e.g. seo tools), with the remaining 23.7% categorised as branded searches ( e.g. Ahrefs).

AIOs are 1.9x more likely to appear on non-branded queries, triggering on 13.1% of all branded queries and 24.9% of non-branded queries in our SERP database.

Compared to the baseline, AI Overviews rarely appear for 1-3 word queries, but often trigger for 5-7+ word queries.

It seems that the longer the search query, the greater the chance an AI Overview will appear. AIOs appear on just 9.5% of single-word queries, but that figure jumps to 46.4% of all queries with seven or more words.

66.5% of keywords that trigger AIOs are categorized as questions.

In total, AIOs appear on 57.9% of all question queries, while non-question queries show a lower rate of AI Overviews compared with the baseline, at 15.5%.

There seems to be little obvious correlation between keyword CPC buckets and AI Overview appearance, with most hovering within a couple of percentage points of our 20.5% baseline:

Almost a third (32.3%) of the keywords that trigger AI Overviews are categorised as YMYL (Your Money or Your Life) queries.

Given that YMYL queries are—according to Google themselves—deserving of extra care and attention, it seems surprising to see AI-generated answers so prevalent.

In fact, AI Overviews are more common for YMYL queries than normal queries. 34.3% of all YMYL queries trigger an AI Overview, far higher than our 20.5% baseline. Non-YMYL queries are less likely to trigger AIOs, at just 17.2%:

All YMYL categories—Medical, Financial, Safety, Legal, and Other—show an increased occurrence of AI Overviews.

This is especially true for Medical YMYL queries, with 44.1% of medical queries triggering an AI Overview—more than double the frequency at which AI overviews appear across all keywords.

This has not gone unnoticed by SEOs in the healthcare industry:

If we categorise keywords by the industry they belong to, we can see that AI Overviews have hit some industries harder than others.

Compared to our baseline of 20.5%, the hardest hit categories are:

At the other end of the spectrum, AI Overviews seem unlikely to trigger for other industries, especially those related to commerce and news content:

Almost all keywords that trigger AI Overviews fall into the not newsy category, with just 0.2% of keywords categorised as very newsy.

Relative to the 20.5% overall AIO rate, very newsy keywords are significantly less likely to trigger an AI Overview, suggesting that AIOs concentrate on evergreen queries, not current news.

As part of a bug bounty, Mark Williams-Cook found a series of query classifiers used by Google as part of their search systems. (Learn more here.)

All but one of these categories (other) are much more likely than average to trigger an AI Overview. At the extreme, 59.8% of all reason queries trigger an AI Overview, the greatest percentage of any category in this research.

AI Overviews generally don’t trigger for NSFW queries. 99.1% of the queries that trigger AIOs are classified as not NSFW:

Only 4% of NSFW queries trigger an AI Overview, far lower than our baseline occurrence:

Relative to the 20.5% overall AIO rate, all NSFW categories show a significantly lower incidence of AI Overviews. Within NSFW, the highest AIO rates are observed for drug queries (12.6%) and scam queries (11.3%), though both remain well below the baseline.

AI Overviews seem unlikely to trigger for local searches (e.g. dentist near me).

AIOs appear for just 7.9% of queries categorised as local searches, well below the base rate of 20.5% across all keywords, and for 22.8% of non-local queries, slightly above the base rate.

Google acknowledges four types of user intent in its Search Quality Evaluator Guidelines:

99.9% of the keywords that trigger AIOs fall into the “Know” category, suggesting strong overlap between Know keywords and our definition of Informational keywords (which also account for 99.9% of AIO triggering keywords). Google seems unlikely to trigger AIOs for other intent types.

Do, Visit-in-person, and Website all trigger AIOs less frequently than the base rate, with Website queries returning them less than 1% of the time.

The Visit in person AIO rate is virtually on par with our Local queries category (7.1% and 7.9% AIO rate respectively); and the Website AIO rate is identical to our Navigational classification from earlier (both returning an AIO rate of 0.9%).

It seems crystal clear that AI Overviews are designed to trigger for informational queries, particularly questions and long queries. They are unlikely to trigger for news queries, local searches, and NSFW queries.

But more surprising: AI Overviews trigger very frequently for YMYL queries, and especially medical YMYL queries. Despite obvious risks of hallucination, Google seems perfectly happy answering crucial medical queries with an AI-generated snippet.