Claude Sonnet 5.5 vs Gemini 3.1 Pro Preview
Which one to choose
Pick Claude Sonnet 5.5 for agentic coding and computer-use work where tasks should finish in few steps and you want a released, current model; pick Gemini 3.1 Pro for hard multi-step problems that mix text, images and planning, when you accept that a preview can change. Both think before answering, call tools, read images and return schema-bound JSON, so the choice is about working style and release status.
Pricing comparison
| Claude Sonnet 5.5 | Gemini 3.1 Pro Preview | |
|---|---|---|
| Model maker | Anthropic | |
| Delivery availability | Available | Available |
| Context window | 1M | 1M |
| Max output | 128K | 64K |
| Official price | Input$2.00per 1M tokensOutput$10.00per 1M tokens | Input$2.00per 1M tokensOutput$12.00per 1M tokens |
| TokenLab price | Input$0.60per 1M tokensOutput$3.00per 1M tokens | Input$1.00per 1M tokensOutput$6.00per 1M tokens |
| Model performance |
|
|
| Capabilities | JSON modePrompt CacheReasoningTool useVision | JSON modePrompt CacheTool useVision |
Choose Claude Sonnet 5.5 when
- You run agent loops over a terminal or a desktop and want tool calls batched so tasks take fewer steps.
- You want to turn up-front thinking off for fast replies and keep it on only when a step needs it.
- You need a model with a fixed release that will not be swapped for a stable version later.
Choose Gemini 3.1 Pro Preview when
- You hand the model hard debugging or planning problems where a wrong first answer is expensive.
- You send diagrams, charts or UI screenshots together with a long written question.
- You work in Gemini-native request style and can re-test when Google promotes the preview to a stable Pro.
How they differ
| Aspect | Claude Sonnet 5.5 | Gemini 3.1 Pro Preview |
|---|---|---|
| Positioning | Anthropic's speed-and-intelligence Sonnet for everyday coding, agents and computer use. | Google's reasoning-first Pro model, aimed at complex problem-solving and agentic coding. |
| Thinking control | Up-front thinking can be reduced with the between_tools setting, trading depth for speed. | Built-in thinking is part of the design; the model reasons before it answers on multi-step tasks. |
| Tool use | Batches tool calls to cut steps, but forced tool use returns an error. | Tool calling supports edit-and-test loops without the forced-tool restriction noted for Sonnet. |
| Sampling parameters | Non-default temperature, top_p and top_k values are rejected. | Sampling settings are not restricted. |
| Release status | Released on September 28, 2026 and described as Anthropic's current Sonnet. | Offered as a preview, so behavior may change or the model may be retired for a stable Pro. |
Summary
- Claude Sonnet 5.5: Input $0.60 / Output $3.00 per 1M tokens; Gemini 3.1 Pro Preview: Input $1.00 / Output $6.00 per 1M tokens. Rates depend on the billing unit, specification, and usage. Compare matching conditions in the model's detailed pricing; a single rate does not determine the total cost.
- Claude Sonnet 5.5 supports 2.0x more output tokens
FAQ
Is Claude Sonnet 5.5 or Gemini 3.1 Pro better for coding?
Neither wins across the board. Sonnet 5.5 is built for agentic coding with batched tool calls and fewer steps per task. Gemini 3.1 Pro suits debugging and planning that need deep reasoning. Run both on your own repository tasks and compare the finished diffs.
Can I swap Gemini 3.1 Pro for Claude Sonnet 5.5 without changing prompts?
Mostly yes for plain prompts, but check three things: Sonnet 5.5 rejects non-default temperature, top_p and top_k, errors on forced tool use, and handles thinking through its own settings. Prompts that rely on those need edits.
Which one handles images?
Both accept images with text in the same request. Gemini 3.1 Pro is described for diagram, chart and UI analysis; Sonnet 5.5 is shown reading screenshots in computer-use tasks.
Which one is safer to build a product on?
Sonnet 5.5 is a released model. Gemini 3.1 Pro is a preview, so Google may change it or move to a stable Pro release. If you need a fixed target, pick Sonnet 5.5 or plan a re-test.
Which is cheaper, Claude Sonnet 5.5 or Gemini 3.1 Pro Preview?
Claude Sonnet 5.5: Input $0.60 / Output $3.00 per 1M tokens; Gemini 3.1 Pro Preview: Input $1.00 / Output $6.00 per 1M tokens. Rates depend on the billing unit, specification, and usage. Compare matching conditions in the model's detailed pricing; a single rate does not determine the total cost.
What are the key differences between Claude Sonnet 5.5 and Gemini 3.1 Pro Preview?
Claude Sonnet 5.5: Reasoning
Sources
Reviewed Oct 2, 2026