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Gemini 3.1 Pro Preview: Advanced Model for Multimodal Reasoning and Agents
Gemini 3.1 Pro Preview is Google’s preview model built to refine the performance and reliability of the Gemini 3 Pro series. It is designed to provide better thinking, improved token efficiency, and a more grounded experience for complex real-world tasks.
Gemini 3.1 Pro Preview is intended for software engineering, advanced multimodal understanding, agentic workflows, tool use, and multi-step execution. Compared with Gemini 3.1 Flash-Lite, it offers stronger reasoning and broader task capability; compared with Gemini 3.5 Flash, it remains a preview Pro-series model rather than the stable Flash option.
Gemini 3.1 Pro Preview: Key Specs
Below are Gemini 3.1 Pro Preview's main specs and how they translate into real-world behavior.
- Context Window - 1,048,576 input tokens: This large input limit lets Gemini 3.1 Pro Preview process long codebases, large document collections, extensive PDFs, video files, and multi-source context in a single workflow.
- Maximum Output Length - 65,536 tokens: This output capacity supports long analytical answers, structured reports, code explanations, and detailed implementation plans.
- Speed and Efficiency - Not officially disclosed: Google does not publish a specific latency value for Gemini 3.1 Pro Preview, so it should be selected primarily for reasoning quality and advanced workflow capability rather than a verified speed number.
- Cost Efficiency - $2.00 input and $12.00 output per 1M tokens for prompts up to 200K tokens: Pricing increases for longer prompts, so Gemini 3.1 Pro Preview is best suited for higher-value tasks where advanced reasoning and multimodal capability justify the cost.
- Reasoning Capability - Thinking with high default reasoning: Gemini 3.1 Pro Preview supports thinking levels and is optimized for reliable multi-step execution, making it useful for complex coding, tool use, and analytical workflows.
- Multimodal Capabilities - Text, image, video, audio, and PDF input with text output: The model can combine different input formats for advanced multimodal understanding, including visual reasoning, document review, and media analysis.
Compare Gemini 3.1 Pro Preview, Gemini 3.5 Flash, and Gemini 3.1 Flash-Lite
A brief overview of how each model differs in power, speed, and use cases.
| Feature | Gemini 3.1 Pro Preview | Gemini 3.5 Flash | Gemini 3.1 Flash-Lite |
|---|---|---|---|
| Knowledge Cutoff | January 2025 | January 2025 | January 2025 |
| Context Window (Tokens) | 1,048,576 input tokens | 1,048,576 input tokens | 1,048,576 input tokens |
| Max Output Tokens | 65,536 | 65,536 | 65,536 |
| Input Modalities | Text, image, video, audio, PDF | Text, image, video, audio, PDF | Text, image, video, audio, PDF |
| Output Modalities | Text | Text | Text |
| Latency (OpenRouter Data) | Not officially disclosed. | Not officially disclosed. | Low latency |
| Speed | Not officially disclosed. | Fast | Fast |
| Input / Output Cost per 1M Tokens | $2.00 / $12.00 for prompts <=200K tokens; $4.00 / $18.00 for prompts >200K tokens | $1.50 / $9.00 | $0.25 text/image/video input or $0.50 audio input / $1.50 output |
| Reasoning Performance | Advanced | Advanced | Practical |
| Coding Performance (on SWE-bench Verified) | 54.2% on SWE-Bench Pro; 70.3% on Terminal-Bench 2.1 | 55.1% on SWE-Bench Pro; 76.2% on Terminal-Bench 2.1 | Not officially disclosed. |
| Best For | advanced multimodal reasoning, software engineering, agentic workflows, tool use, and complex analysis | agentic coding, multi-step workflows, long-context reasoning, multimodal tasks, and scaled professional applications | high-volume lightweight tasks, translation, extraction, routing, summarization, multimodal processing, and cost-efficient agentic workflows |
Best Cases to Use Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview is best suited for complex tasks that need advanced reasoning, multimodal understanding, software engineering behavior, and precise tool use.
- For software engineering: Use Gemini 3.1 Pro Preview to analyze code, identify bugs, reason through architecture, plan implementations, and support advanced coding workflows.
- For agentic workflows: Build agents that use tools, execute multi-step plans, preserve reasoning context, and operate across documents, code, files, and external systems.
- For multimodal research: Analyze text, PDFs, images, audio, and video together to generate structured summaries, comparisons, and evidence-based outputs.
- For enterprise knowledge work: Review large documents, extract insights, compare information across sources, and produce reports for business or technical teams.
- For tool-heavy applications: Combine function calling, structured outputs, search grounding, URL context, code execution, and file search to build capable AI workflows.
- For complex analysis: Use the model for tasks that require broad world knowledge, careful reasoning across modalities, and reliable multi-step execution.
How to Access Gemini 3.1 Pro Preview
Accessing Gemini 3.1 Pro Preview depends on whether you need official API control or a simple chat interface for advanced reasoning and multimodal work.
1. Official API
You can access Gemini 3.1 Pro Preview through the official Gemini API using the gemini-3.1-pro-preview model ID. Google also lists a gemini-3.1-pro-preview-customtools endpoint for workflows that use custom tools and bash-style tool execution.
2. EssayDone AI Chat
If you want to use Gemini 3.1 Pro Preview without API setup, EssayDone AI Chat provides access to this model through an easy-to-use chat interface.
This option is useful for users who want advanced help with coding, research, document analysis, writing, study, and multimodal reasoning without managing API keys or technical configuration.
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FAQ
Here are some frequently asked questions about Gemini 3.1 Pro Preview.
Yes. Gemini 3.1 Pro Preview supports thinking and is optimized for advanced reasoning, software engineering, multimodal understanding, and reliable multi-step execution.
Gemini 3.1 Pro Preview costs $2.00 per 1M input tokens and $12.00 per 1M output tokens for prompts up to 200K tokens. For prompts above 200K tokens, standard pricing is $4.00 per 1M input tokens and $18.00 per 1M output tokens.
Gemini 3.1 Pro Preview is optimized for software engineering, agentic workflows, precise tool use, multimodal reasoning, complex analysis, and grounded multi-step tasks.
Gemini 3.1 Pro Preview accepts text, image, video, audio, and PDF inputs and produces text output. It is useful for advanced multimodal analysis, document review, visual reasoning, and media understanding.
Compared with Gemini 3.5 Flash, Gemini 3.1 Pro Preview is a preview Pro-series model focused on advanced reasoning and software engineering behavior. Compared with Gemini 3.1 Flash-Lite, it is more capable for complex tasks but more expensive.
Using Gemini 3.1 Pro Preview in EssayDone AI Chat gives users a simple way to apply advanced Gemini reasoning to coding, research, writing, and multimodal analysis without configuring the official API.