Claude Sonnet 4.5 vs Gemini 3.1 Pro Preview
Claude Sonnet 4.5 (2025) and Gemini 3.1 Pro Preview (2026) are frontier reasoning models from Anthropic and Google DeepMind. Claude Sonnet 4.5 ships a 200K-token context window, while Gemini 3.1 Pro Preview ships a 1M-token context window. On pricing, Gemini 3.1 Pro Preview costs $2/1M input tokens versus $3/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Gemini 3.1 Pro Preview is ~50% cheaper at $2/1M; pay for Claude Sonnet 4.5 only for reasoning depth.
Decision scorecard
Local evidence first| Signal | Claude Sonnet 4.5 | Gemini 3.1 Pro Preview |
|---|---|---|
| Decision fit | RAG, Agents, and Long context | Coding, RAG, and Agents |
| Context window | 200K | 1M |
| Cheapest output | $15/1M tokens | $12/1M tokens |
| Provider routes | 7 tracked | 4 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Claude Sonnet 4.5 has broader tracked provider coverage for fallback and procurement flexibility.
- Claude Sonnet 4.5 uniquely exposes Reasoning in local model data.
- Local decision data tags Claude Sonnet 4.5 for RAG, Agents, and Long context.
- Gemini 3.1 Pro Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3.1 Pro Preview has the lower cheapest tracked output price at $12/1M tokens.
- Gemini 3.1 Pro Preview uniquely exposes Code execution in local model data.
- Local decision data tags Gemini 3.1 Pro Preview for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output prices on this page.
Claude Sonnet 4.5
$6,150
Cheapest tracked route: Microsoft Foundry
Gemini 3.1 Pro Preview
$4,600
Cheapest tracked route: Google AI Studio
Estimated monthly gap: $1,550. Batch, cache, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on GCP Vertex AI, OpenRouter, and Replicate API; start route-level A/B tests there.
- Gemini 3.1 Pro Preview is $3/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning before moving production traffic.
- Gemini 3.1 Pro Preview adds Code execution in local capability data.
- Provider overlap exists on GCP Vertex AI, Replicate API, and OpenRouter; start route-level A/B tests there.
- Claude Sonnet 4.5 is $3/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Code execution before moving production traffic.
- Claude Sonnet 4.5 adds Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-09-29 | 2026-02-19 |
| Context window | 200K | 1M |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-12 | 2025-01 |
Pricing and availability
| Pricing attribute | Claude Sonnet 4.5 | Gemini 3.1 Pro Preview |
|---|---|---|
| Input price | $3/1M tokens | $2/1M tokens |
| Output price | $15/1M tokens | $12/1M tokens |
| Providers |
Capabilities
| Capability | Claude Sonnet 4.5 | Gemini 3.1 Pro Preview |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | Yes |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on reasoning mode: Claude Sonnet 4.5 and code execution: Gemini 3.1 Pro Preview. Both models share vision, multimodal input, function calling, and tool use, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Claude Sonnet 4.5 lists $3/1M input and $15/1M output tokens, while Gemini 3.1 Pro Preview lists $2/1M input and $12/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Gemini 3.1 Pro Preview lower by about $1.6 per million blended tokens. Availability is 7 providers versus 4, so concentration risk also matters.
Choose Claude Sonnet 4.5 when reasoning depth and broader provider choice are central to the workload. Choose Gemini 3.1 Pro Preview when coding workflow support, larger context windows, and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions.
FAQ
Which has a larger context window, Claude Sonnet 4.5 or Gemini 3.1 Pro Preview?
Gemini 3.1 Pro Preview supports 1M tokens, while Claude Sonnet 4.5 supports 200K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Sonnet 4.5 or Gemini 3.1 Pro Preview?
Gemini 3.1 Pro Preview is cheaper on tracked token pricing. Claude Sonnet 4.5 costs $3/1M input and $15/1M output tokens. Gemini 3.1 Pro Preview costs $2/1M input and $12/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Sonnet 4.5 or Gemini 3.1 Pro Preview open source?
Claude Sonnet 4.5 is listed under Proprietary. Gemini 3.1 Pro Preview is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Claude Sonnet 4.5 or Gemini 3.1 Pro Preview?
Both Claude Sonnet 4.5 and Gemini 3.1 Pro Preview expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for multimodal input, Claude Sonnet 4.5 or Gemini 3.1 Pro Preview?
Both Claude Sonnet 4.5 and Gemini 3.1 Pro Preview expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Claude Sonnet 4.5 and Gemini 3.1 Pro Preview?
Claude Sonnet 4.5 is available on Microsoft Foundry, Anthropic, Snowflake Cortex, GCP Vertex AI, and AWS Bedrock. Gemini 3.1 Pro Preview is available on Google AI Studio, GCP Vertex AI, OpenRouter, and Replicate API. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-19. Data sourced from public model cards and provider documentation.