Claude Sonnet 4.5 vs DeepSeek V3.1
Claude Sonnet 4.5 (2025) and DeepSeek V3.1 (2026) are frontier reasoning models from Anthropic and DeepSeek. Claude Sonnet 4.5 ships a 200K-token context window, while DeepSeek V3.1 ships a 64K-token context window. On MMLU PRO, Claude Sonnet 4.5 leads by 2.7 pts. On pricing, DeepSeek V3.1 costs $0.56/1M input tokens versus $3/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
DeepSeek V3.1 is ~436% cheaper at $0.56/1M; pay for Claude Sonnet 4.5 only for reasoning depth.
Specs
| Released | 2025-09-29 | 2026-03-01 |
| Context window | 200K | 64K |
| Parameters | — | — |
| Architecture | decoder only | mixture of experts |
| License | Proprietary | Open Source |
| Knowledge cutoff | 2025-12 | - |
Pricing and availability
| Claude Sonnet 4.5 | DeepSeek V3.1 | |
|---|---|---|
| Input price | $3/1M tokens | $0.56/1M tokens |
| Output price | $15/1M tokens | $1.68/1M tokens |
| Providers |
Capabilities
| Claude Sonnet 4.5 | DeepSeek V3.1 | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
| Benchmark | Claude Sonnet 4.5 | DeepSeek V3.1 |
|---|---|---|
| MMLU PRO | 86.0 | 83.3 |
Deep dive
On shared benchmark coverage, MMLU PRO has Claude Sonnet 4.5 at 86 and DeepSeek V3.1 at 83.3, with Claude Sonnet 4.5 ahead by 2.7 points. The largest visible gap is 2.7 points on MMLU PRO, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on reasoning mode: Claude Sonnet 4.5, function calling: Claude Sonnet 4.5, tool use: Claude Sonnet 4.5, and code execution: DeepSeek V3.1. Both models share vision, multimodal input, and structured outputs, 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 DeepSeek V3.1 lists $0.56/1M input and $1.68/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts DeepSeek V3.1 lower by about $5.7 per million blended tokens. Availability is 8 providers versus 6, so concentration risk also matters.
Choose Claude Sonnet 4.5 when reasoning depth, larger context windows, and broader provider choice are central to the workload. Choose DeepSeek V3.1 when coding workflow support 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.
FAQ
Which has a larger context window, Claude Sonnet 4.5 or DeepSeek V3.1?
Claude Sonnet 4.5 supports 200K tokens, while DeepSeek V3.1 supports 64K 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 DeepSeek V3.1?
DeepSeek V3.1 is cheaper on tracked token pricing. Claude Sonnet 4.5 costs $3/1M input and $15/1M output tokens. DeepSeek V3.1 costs $0.56/1M input and $1.68/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Sonnet 4.5 or DeepSeek V3.1 open source?
Claude Sonnet 4.5 is listed under Proprietary. DeepSeek V3.1 is listed under Open Source. 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 DeepSeek V3.1?
Both Claude Sonnet 4.5 and DeepSeek V3.1 expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Claude Sonnet 4.5 or DeepSeek V3.1?
Both Claude Sonnet 4.5 and DeepSeek V3.1 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 DeepSeek V3.1?
Claude Sonnet 4.5 is available on Microsoft Foundry, Anthropic, Snowflake Cortex, GCP Vertex AI, and AWS Bedrock. DeepSeek V3.1 is available on Microsoft Foundry, Fireworks AI, NVIDIA NIM, Together AI, and AWS Bedrock. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-04-24. Data sourced from public model cards and provider documentation.