Gemini 3.1 Pro

Learning Objectives

• Understand Gemini 3.1 Pro's capabilities and benchmark performance
• Identify what Deep Think mode adds for complex reasoning tasks
• Compare Gemini 3.1 Pro to competing frontier models

What Is Gemini 3.1 Pro?

Gemini 3.1 Pro is Google DeepMind's previous flagship foundation model, released in February 2026 and succeeded by Gemini 4 Argon in October. It achieves 94.3% on GPQA Diamond (the highest score recorded at its launch), 77.1% on ARC-AGI-2, and ranked first on more than twelve major benchmarks when it was released. Newer frontier models have since passed several of those marks, including OpenAI's GPT-6 Astra on GPQA Diamond.

With 1 million token context, native multimodal input (text, image, video, audio), and a Deep Think reasoning mode, Gemini 3.1 Pro is designed for the most demanding enterprise and research use cases.

Its Successor: Gemini 4 Argon

On September 30, 2026 Google announced Gemini 4 Argon, its next frontier model and the first new flagship since this one, and on October 13 it made Argon generally available. It skips the Gemini 3.5 Pro that Google announced in May and never released. Google reports leading scores on long-horizon coding and professional-work benchmarks and an output limit of 1 million tokens, up from 64,000.

Pricing & Access

Core Capabilities

Frontier Reasoning

94.3% GPQA Diamond, 77.1% ARC-AGI-2, and top scores across MATH, HumanEval, and natural language benchmarks. Gemini 3.1 Pro excels at graduate-level science, complex mathematics, code generation, and multi-step logical reasoning.

1 million Token Context

Process entire codebases, lengthy legal documents, research paper collections, or hours of video in a single prompt. The 1 million token window enables use cases impossible with shorter-context models.

Native Multimodal

Accepts text, images, video, and audio as input natively — not through separate models or adapters. This enables tasks like analyzing a video while referencing a technical document, or extracting data from images within a larger text analysis.

Deep Think Mode

Extended reasoning mode that allows the model to "think longer" on complex problems — trading speed for accuracy on tasks that benefit from deeper analysis. Similar in concept to OpenAI's o-series reasoning models.

Strengths

• Strong reasoning benchmarks: 94.3% GPQA Diamond and first place on more than twelve benchmarks at its February 2026 launch
• 1 million token context: Among the largest context windows available
• True multimodal: Native text, image, video, and audio input
• Deep Think mode: Extended reasoning for the hardest problems
• Google ecosystem: Integrates with Vertex AI, Google Workspace, and Android

Limitations & Considerations

• Latency: Deep Think mode is significantly slower than standard inference
• Cost: Frontier-tier pricing — more expensive than Flash or Lite variants
• Google dependency: Deepest integration within Google Cloud ecosystem
• Preview status: Some capabilities still in preview as of early 2026

When to choose alternatives:

• Cost-sensitive tasks → Gemini Flash or Nova 2 Lite
• Data sovereignty → Cohere Command A (on-premise) or Mistral (EU)
• Maximum coding performance → a closed frontier flagship from Anthropic or OpenAI, such as an Opus-class Claude model or OpenAI's GPT-6 series
• Open-source → DeepSeek V3.2, Qwen3.5, or Llama 4

Key Takeaways

• Gemini 3.1 Pro scored 94.3% on GPQA Diamond at its February 2026 launch, with 1 million token context and native multimodal input
• Gemini 4 Argon replaced 3.1 Pro as Google's flagship when it became generally available on October 13, 2026; Google is keeping 3.1 Pro available for now
• Deep Think mode trades speed for accuracy on the hardest reasoning tasks
• Available via Google AI Studio (free tier), Vertex AI (enterprise), and the Gemini consumer app
• Best for demanding reasoning, long-document analysis, and multimodal tasks within the Google ecosystem