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Google DeepMindGemini 3.5 familyDeprecatedReasoning modelReleased 19 May 2026

Gemini 3.5 Flash

First model of the Gemini 3.5 generation (I/O, May 2026). Kept for compatibility; newer 3.6-3.8 Flash models are cheaper and stronger.

Model idgemini-3.5-flash

Price$1.50 in, $9 out per 1M tokens

Checked10 October 2026

No published training cutoff

At least1,842events since its release on 19 May 2026

83 historic, 422 major. 178 days of news.

Google DeepMind doesn’t publish a training cutoff, so we count from its release date. The real gap is larger.

How to call it

3 ways to use Gemini 3.5 Flash, with the model id each provider expects.

Providers, model ids, endpoints and docs for Gemini 3.5 Flash
ProviderModel idEndpointDocs
Gemini API gemini-3.5-flash https://generativelanguage.googleapis.com/v1beta/models/gemini-3.5-flash:generateContent ai.google.dev
Google Cloud Gemini Enterprise Agent Platform (Vertex AI) gemini-3.5-flash docs.cloud.google.com
OpenRouter google/gemini-3.5-flash

Pricing

Prices for Gemini 3.5 Flash
Input$1.50 per 1M tokens
Output$9 per 1M tokens

As published: “per 1M tokens (Standard tier)”.

Source: ai.google.dev, checked 10 October 2026.

Specs

Input
Text, images, audio, video and PDF
Output
Text
Context window
1,048,576 tokens
Max output
65,536 tokens
Open weights
No
Licence
Proprietary
Training cutoff
Not published
Released
19 May 2026
Status
Deprecated
Type
Reasoning model

What stands out

What its maker marketed at launch, and what people found later, each with its source.

  • Flash beats previous Pro on agents

    Outperformed Gemini 3.1 Pro on Terminal-Bench 2.1 (76.2%), GDPval-AA (1656 Elo) and MCP Atlas (83.6%); 84.2% CharXiv Reasoning.

    Source: blog.google

  • High output speed

    Google claims ~4x the output tokens/second of other frontier models at launch.

    Source: blog.google

Notes

Deprecated on 2026-10-08: all requests to gemini-3.5-flash are now automatically routed to gemini-3.6-flash (Gemini API changelog, https://ai.google.dev/gemini-api/docs/changelog). Use gemini-3.8-flash (or 3.6-flash). Launched at Google I/O 2026 as first Gemini 3.5 model. Model page lists gemini-3-flash-preview (Dec 2025) as its preview predecessor id; that preview is still served. Now more expensive than 3.6-3.8 Flash; use gemini-3.8-flash.

curl "https://generativelanguage.googleapis.com/v1beta/models/gemini-3.5-flash:generateContent" \
  -H "x-goog-api-key: $GEMINI_API_KEY" -H "Content-Type: application/json" \
  -d '{"contents":[{"parts":[{"text":"Hello"}]}]}'

Sources: model page, pricing, deprecations, I/O blog.