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Google DeepMindGemini 3 familyPreviewReasoning modelReleased 19 Feb 2026

Gemini 3.1 Pro

Google’s Pro-tier reasoning model (preview), the newest one in the Gemini API until Gemini 4 Argon became generally available on 2026-10-13 (Google has announced no deprecation; it stays in the Gemini app model picker per 9to5Google). Good for hard reasoning, long-context analysis and complex code, though 3.8 Flash is often better value.

Model idgemini-3.1-pro-preview

Price$2 in, $12 out per 1M tokens

Checked12 October 2026

Knows up to January 2025

2,037events after its cutoff

90 historic, 476 major. 651 days of news.

It launched on 19 February 2026, already missing 110 of them. Coverage before 2026 is thin (80 entries for 2025), so this count is a floor.

Five things it has never heard of

Its cutoff, January 2025, is before this chart starts: every mark here is news it has never seen.

How to call it

4 ways to use Gemini 3.1 Pro, with the model id each provider expects.

Providers, model ids, endpoints and docs for Gemini 3.1 Pro
ProviderModel idEndpointDocs
Gemini API gemini-3.1-pro-preview https://generativelanguage.googleapis.com/v1beta/models/gemini-3.1-pro-preview:generateContent ai.google.dev
Google Cloud Gemini Enterprise Agent Platform (Vertex AI) docs.cloud.google.com
OpenRouter google/gemini-3.1-pro-preview
Web app gemini.google.com

Pricing

Prices for Gemini 3.1 Pro
Input$2 per 1M tokens
Output$12 per 1M tokens

As published: “per 1M tokens (Standard, prompts <=200k; >200k: $4.00 in / $18.00 out)”.

Source: ai.google.dev, checked 12 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
January 2025
Released
19 February 2026
Status
Preview
Type
Reasoning model

What stands out

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

  • Novel-pattern reasoning

    Verified 77.1% on ARC-AGI-2, more than double Gemini 3 Pro.

    Source: blog.google

  • Custom-tools agent variant

    Separate id gemini-3.1-pro-preview-customtools tuned for agentic workflows using custom tools and bash.

    Source: ai.google.dev

  • Code-generated visuals

    Showcased animated SVG generation, live dashboards and interactive 3D experiences from prompts.

    Source: blog.google

Four assistants, one scale

Gemini 3.1 Pro is added as a fifth row. Each row runs from what the model knows (graphite) through the months between its cutoff and its launch (hatched) to today (pink).

  1. GPT-6 Astra 271 at launch, 1,863 today
  2. Claude Opus 5.5 372 at launch, 1,795 today
  3. Gemini 4 Hydrogen 1,863 at launch, 1,889 today
  4. Grok 4.7 387 at launch, 1,829 today
  5. Gemini 3.1 Pro 110 at launch, 2,037 today
Show as a table
ModelCutoffReleasedMissing at launchMissing today
GPT-6 AstraApril 20263 September 20262711,863
Claude Opus 5.5June 202622 September 20263721,795
Gemini 4 HydrogenMarch 202612 November 20261,8631,889
Grok 4.7May 202621 September 20263871,829
Gemini 3.1 ProJanuary 202519 February 20261102,037

Notes

Knowledge cutoff January 2025: Google’s Gemini 3.1 Pro model card gives no date and says the model ‘is based on Gemini 3 Pro’, whose model card states January 2025 (storage.googleapis.com/deepmind-media/Model-Cards/Gemini-3-Pro-Model-Card.pdf); so the newest Pro knows a year less than the Flash models (March 2026). The newest Pro-tier model callable in the Gemini API (preview). Gemini 3.5 Pro, announced at I/O 2026, has not shipped; Google’s new top model is Gemini 4 Argon (announced 2026-09-30, which replaces the ‘3.x Pro’ naming), but at launch it was open only to the Fairwind cyber-defense program, with paid API access announced as next and no date. Predecessor gemini-3-pro-preview is shut down. Newer 3.5+ Flash models beat it on many agentic and coding benchmarks at lower cost.

curl "https://generativelanguage.googleapis.com/v1beta/models/gemini-3.1-pro-preview:generateContent" \
  -H "x-goog-api-key: $GEMINI_API_KEY" -H "Content-Type: application/json" \
  -d '{"contents":[{"parts":[{"text":"Prove that sqrt(2) is irrational"}]}]}'

Sources: model page, pricing, launch blog, Gemini 4 Argon announcement.

Not yet checked against an official source: Vertex model id not verified.