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Google: Gemini 3.1 Pro Preview Custom Tools vs Google: Gemini 3 Flash Preview: Complete Comparison 2026

Choosing between Google: Gemini 3.1 Pro Preview Custom Tools and Google: Gemini 3 Flash Preview? We compare both tools across features, pricing, pros and cons to help you decide which is the better fit in 2026.

Google: Gemini 3.1 Pro Preview Custom Tools9.2

Google · Video & Audio, Chatbots & LLMs

Gemini 3.1 Pro Preview Custom Tools is a variant of Gemini 3.1 Pro that improves tool selection behavior by preventing overuse of a general bash tool when more efficient third-party...

Google: Gemini 3 Flash Preview9.2

Google · Video & Audio, Chatbots & LLMs

Gemini 3 Flash Preview is a high speed, high value thinking model designed for agentic workflows, multi turn chat, and coding assistance. It delivers near Pro level reasoning and tool...

Key differences at a glance

  • •Both start at $2.00/1M tokens (Google: Gemini 3.1 Pro Preview Custom Tools) and $0.50/1M tokens (Google: Gemini 3 Flash Preview).
  • •Context windows differ: Google: Gemini 3.1 Pro Preview Custom Tools offers 1,048,756 tokens, Google: Gemini 3 Flash Preview offers 1,048,576 tokens.

Side-by-side comparison

FeatureGoogle: Gemini 3.1 Pro Preview Custom ToolsGoogleGoogle: Gemini 3 Flash PreviewGoogle
Quality score9.2 / 109.2 / 10
Starting price$2.00/1M tokens$0.50/1M tokens
Free tierNoNo
API input price$2 / 1M tokens$0.5 / 1M tokens
API output price$12 / 1M tokens$3 / 1M tokens
Speed——
Context window1,048,756 tokens1,048,576 tokens
CategoriesVideo & Audio, Chatbots & LLMsVideo & Audio, Chatbots & LLMs
Key features
  • 1,048,756-token context window
  • Vision (image input)
  • Reasoning / chain-of-thought
  • Tool / function calling
  • 1,048,576-token context window
  • Vision (image input)
  • Reasoning / chain-of-thought
  • Tool / function calling
Pros
      Cons

          Google: Gemini 3.1 Pro Preview Custom Tools

          Choose Google: Gemini 3.1 Pro Preview Custom Tools if you want content creation, research and writing.

          Google: Gemini 3 Flash Preview

          Choose Google: Gemini 3 Flash Preview if you want content creation, research and writing.

          Pricing comparison

          Google: Gemini 3.1 Pro Preview Custom Tools
          $2.00/1M tokens
          API: $2 in / $12 out per 1M tokens
          Google: Gemini 3 Flash Preview
          $0.50/1M tokens
          API: $0.5 in / $3 out per 1M tokens

          The verdict

          Overall, Google: Gemini 3.1 Pro Preview Custom Tools edges ahead with a quality score of 9.2 versus 9.2 for Google: Gemini 3 Flash Preview. Choose Google: Gemini 3.1 Pro Preview Custom Tools if you want . That said, Google: Gemini 3 Flash Preview is the better pick when matters most — so the right answer depends on your priorities and budget.

          Try Google: Gemini 3.1 Pro Preview Custom Tools →Try Google: Gemini 3 Flash Preview →

          Frequently asked questions

          Q. Which is better, Google: Gemini 3.1 Pro Preview Custom Tools or Google: Gemini 3 Flash Preview?

          On our scoring, Google: Gemini 3.1 Pro Preview Custom Tools edges ahead (9.2/10), but the right pick depends on your priorities and budget — see the breakdown above.

          Q. Is Google: Gemini 3.1 Pro Preview Custom Tools or Google: Gemini 3 Flash Preview cheaper?

          Google: Gemini 3.1 Pro Preview Custom Tools starts at $2.00/1M tokens and Google: Gemini 3 Flash Preview at $0.50/1M tokens. Check current rates before committing.

          Q. Can I use Google: Gemini 3.1 Pro Preview Custom Tools and Google: Gemini 3 Flash Preview together?

          Yes — many teams use more than one AI tool, picking Google: Gemini 3.1 Pro Preview Custom Tools for some tasks and Google: Gemini 3 Flash Preview for others where it's stronger.