AI search news ·
Which Gemini model powers AI Mode in Google Search now? Gemini 3.8 Flash, for AI Pro and Ultra subscribers from 2026-09-02, Google's third Flash release in six weeks
On 2026-09-02 Google published Introducing Gemini 3.8 Flash and 3.8 Flash Cyber. Its availability line names Search: "3.8 Flash is available to Google AI Pro and Ultra subscribers across the Gemini app, AI Mode in Google Search and Gemini in Google Sheets." Three weeks earlier the same tier got Gemini 3.7 Flash in AI Mode, announced by the Search team a day after that model's launch post, which had not mentioned Search. This time the model post itself says AI Mode. The post says nothing about free-tier AI Mode, nothing about AI Overviews, and nothing about whether 3.8 replaces 3.7 in the model menu or sits beside it. We read the post in full; every quotation below is verbatim from it.
Primary source: Google, "Introducing Gemini 3.8 Flash and 3.8 Flash Cyber" (blog.google, 2026-09-02)
What Google said
The post opens: "Building on the momentum of 3.7 Flash from three weeks ago and marking our third Flash release in only six weeks, today we’re introducing Gemini 3.8, our best reasoning & coding model yet, at the same speed and low cost of 3.7." It lists two variants, Gemini 3.8 Flash and Gemini 3.8 Flash Cyber; the second goes to "trusted defenders" through a new Fairwind Program and is not a consumer surface. API pricing is unchanged from 3.7 Flash at $0.75 per million input tokens and $3.75 per million output tokens. The developer section adds that 3.7 Flash stays available: developers can "continue to rely on Gemini 3.7 Flash, which remains fully supported for efficiency-first workloads." The consumer section is the line that matters for anyone measuring what Google's AI answers say about a business: "3.8 Flash is available to Google AI Pro and Ultra subscribers across the Gemini app, AI Mode in Google Search and Gemini in Google Sheets."
| Release | Google's launch post | Named AI Mode in the launch post | Who gets it in AI Mode |
|---|---|---|---|
| Gemini 3.5 Flash-Lite | 2026-07-21 | yes, "also rolling out in Google Search" (our post) | not tiered in the post |
| Gemini 3.7 Flash | 2026-08-13 | no; the Search team announced the AI Mode rollout on 2026-08-14 (our post) | Google AI Pro and Ultra, from the model menu |
| Gemini 3.8 Flash | 2026-09-02 | yes, in the availability line | Google AI Pro and Ultra subscribers |
What the post does not say
- Nothing about the free tier of AI Mode or its default model. In August the trade press reported a model menu with Auto and Pro entries for subscribers; this post does not describe the menu.
- Nothing about AI Overviews, which sit on every Google result page and are not tiered.
- Nothing on whether 3.8 Flash replaces 3.7 Flash for subscribers in AI Mode or is added beside it. The only continuity statement is for the API, where 3.7 Flash "remains fully supported."
- The one behavioural note is about the API, not Search: "At times, the model might use more tokens to maximize performance, especially at higher effort levels."
Why it matters if you care about AI visibility
- The AI Mode answer a paying searcher sees and the one a free searcher sees now come from models released weeks apart, and the paid one changed on 2026-09-02. A read of "how AI Mode describes my business" is worth keeping only with a date and a tier on it.
- An API read is not an AI Mode read. Our own weekly gauge queries the Gemini API on a named model and prints the model id with every run; a report that says "Gemini says X about you" without naming the model and the surface is describing something that may have been swapped out three times since June.
- The useful measurement after a swap is a before-and-after pair on the same questions across the 2026-09-02 boundary. Our free 60-second check reads each engine with a timestamp, which is the minimum a pair needs.
Limits
- One vendor post. We did not verify trade coverage this run; the claims here are Google's own words and our two earlier posts, which cite their sources.
- The post gives no share, no default, and no rollout timing beyond "available"; we do not know what fraction of AI Mode sessions run on 3.8 Flash.
- Whether an answer about a given business changed with the model is an empirical question per business; this post does not answer it.
Which Gemini model powers AI Mode in Google Search?
As of Google's 2026-09-02 post, Gemini 3.8 Flash is available to Google AI Pro and Ultra subscribers in AI Mode, three weeks after Gemini 3.7 Flash reached the same tier. Google has not said which model serves free-tier AI Mode or AI Overviews.
Does Gemini 3.8 Flash replace 3.7 Flash in AI Mode?
Google's post does not say. It states that 3.7 Flash remains fully supported for developers on the API and lists 3.8 Flash as available to subscribers across the Gemini app, AI Mode and Sheets.
Should I re-check what Google AI Mode says about my business after a model change?
Yes, as a dated pair: the same questions before and after 2026-09-02, with the tier and model noted. Three Flash releases in six weeks make any undated answer a poor baseline.
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