As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/m/gemini-3-1-pro/

# Gemini 3.1 Pro

Google DeepMind, Gemini 3 family. Status: preview. Type: reasoning model. Released: 2026-02-19. Training cutoff: 2025-01.

## How to call it

| Provider | Model id | Endpoint | Docs |
|---|---|---|---|
| Gemini API | `gemini-3.1-pro-preview` | https://generativelanguage.googleapis.com/v1beta/models/gemini-3.1-pro-preview:generateContent | https://ai.google.dev/gemini-api/docs/models/gemini-3.1-pro-preview |
| Google Cloud Gemini Enterprise Agent Platform (Vertex AI) |  |  | https://docs.cloud.google.com/gemini-enterprise-agent-platform/models/gemini/3-1-pro |
| OpenRouter | `google/gemini-3.1-pro-preview` |  |  |
| Web app |  |  | https://gemini.google.com |

## Pricing

- Input: $2 per 1M tokens
- Output: $12 per 1M tokens
- Unit as published: per 1M tokens (Standard, prompts <=200k; >200k: $4.00 in / $18.00 out)
- Source: https://ai.google.dev/gemini-api/docs/pricing
- Last checked: 2026-10-12

## Specs

- Input: text, image, audio, video, pdf
- Output: text
- Context window: 1,048,576 tokens
- Max output: 65,536 tokens
- Open weights: no
- Licence: proprietary

## What it has not seen

- Published training cutoff: 2025-01 (January 2025).
- AI events after it on Post-Cutoff: 2,037 (476 major, 90 historic), as of 2026-11-13.
- Already missing at launch: 110.
- Briefings of the news since January 2025: https://postcutoff.com/briefings/cutoff-2025-01-s.md (short), https://postcutoff.com/briefings/cutoff-2025-01-m.md (medium), https://postcutoff.com/briefings/cutoff-2025-01.md (full).
- Its card, with five things it has never heard of: https://postcutoff.com/you/gemini-3-1-pro/

## What stands out

- Novel-pattern reasoning: Verified 77.1% on ARC-AGI-2, more than double Gemini 3 Pro. Source: https://blog.google/innovation-and-ai/models-and-research/gemini-models/gemini-3-1-pro/
- Custom-tools agent variant: Separate id gemini-3.1-pro-preview-customtools tuned for agentic workflows using custom tools and bash. Source: https://ai.google.dev/gemini-api/docs/models/gemini-3.1-pro-preview
- Code-generated visuals: Showcased animated SVG generation, live dashboards and interactive 3D experiences from prompts. Source: https://blog.google/innovation-and-ai/models-and-research/gemini-models/gemini-3-1-pro/

## 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. Vertex model id not verified.

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.

```bash
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](https://ai.google.dev/gemini-api/docs/models/gemini-3.1-pro-preview), [pricing](https://ai.google.dev/gemini-api/docs/pricing), [launch blog](https://blog.google/innovation-and-ai/models-and-research/gemini-models/gemini-3-1-pro/), [Gemini 4 Argon announcement](https://blog.google/innovation-and-ai/models-and-research/gemini-models/gemini-4-argon/).

Model page: https://postcutoff.com/m/gemini-3-1-pro/