Claude Sonnet 4.5 vs DeepSeek V3.1
Claude Sonnet 4.5 (2025) and DeepSeek V3.1 (2025) 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. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Claude Sonnet 4.5 is safer overall; choose DeepSeek V3.1 when coding workflow support matters.
Decision scorecard
Local evidence first| Signal | Claude Sonnet 4.5 | DeepSeek V3.1 |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | multimodal apps and provider-routed production |
| Decision fit | Coding, RAG, and Agents | Coding, Agents, and Vision |
| Context window | 200k | 64k |
| Cheapest output | $15/1M tokens | $1/1M tokens |
| Provider routes | 8 tracked | 8 tracked |
| Shared benchmarks | MMLU PRO leader | 2 rows |
Decision tradeoffs
- Claude Sonnet 4.5 holds a shared-benchmark lead on MMLU PRO, ahead by 2.7 points.
- Claude Sonnet 4.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Claude Sonnet 4.5 uniquely exposes Reasoning, Function calling, and Tool use in local model data.
- Local decision data tags Claude Sonnet 4.5 for Coding, RAG, and Agents.
- DeepSeek V3.1 has the lower cheapest tracked output price at $1/1M tokens.
- DeepSeek V3.1 uniquely exposes Code execution in local model data.
- Local decision data tags DeepSeek V3.1 for Coding, Agents, and Vision.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Claude Sonnet 4.5
$6,150
Cheapest tracked route/tier: Microsoft Foundry
DeepSeek V3.1
$466
Cheapest tracked route/tier: Novita AI
Estimated monthly gap: $5,684. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Microsoft Foundry, AWS Bedrock, and Replicate API; start route-level A/B tests there.
- DeepSeek V3.1 is $14/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning, Function calling, and Tool use before moving production traffic.
- DeepSeek V3.1 adds Code execution in local capability data.
- Provider overlap exists on Microsoft Foundry, AWS Bedrock, and Replicate API; start route-level A/B tests there.
- Claude Sonnet 4.5 is $14/1M 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, Function calling, and Tool use in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-09-29 | 2025-08-21 |
| Context window | 200k | 64k |
| Parameters | — | 671B total, 37B active (MoE) |
| Architecture | decoder only | mixture of experts |
| License | Proprietary | MIT(OSI) |
| Openness | Proprietary | Open source |
| Commercial use | Commercial use with conditions | Commercial use allowed |
| Knowledge cutoff | 2025-12 | - |
Pricing and availability
| Pricing attribute | Claude Sonnet 4.5 | DeepSeek V3.1 |
|---|---|---|
| Input price |
| $0.27/1M tokens |
| Output price |
| $1/1M tokens |
| Providers |
Capabilities
| Capability | Claude Sonnet 4.5 | DeepSeek V3.1 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | Yes |
| Code execution | No | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Claude Sonnet 4.5 | DeepSeek V3.1 |
|---|---|---|
| MMLU PRO | 86.0 | 83.3 |
| SWE-bench Verified | 77.2 | 66.0 |
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; SWE-bench Verified has Claude Sonnet 4.5 at 77.2 and DeepSeek V3.1 at 66, with Claude Sonnet 4.5 ahead by 11.2 points. The largest visible gap is 11.2 points on SWE-bench Verified, 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 tiered pricing: 0-200,001t is $3/1M input and $15/1M output; 200,001t+ is $6/1M input and $22.50/1M output, while DeepSeek V3.1 lists $0.27/1M input and $1/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts DeepSeek V3.1 lower by about $6.11 per million blended tokens. For tiered rows, this cheapest-track view can understate interactive or fast-lane spend, so compare the tier you will actually use. Availability is 8 providers versus 8, so concentration risk also matters.
Choose Claude Sonnet 4.5 when reasoning depth and larger context windows 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?
Claude Sonnet 4.5 lists tiered pricing: 0-200,001t is $3/1M input and $15/1M output; 200,001t+ is $6/1M input and $22.50/1M output. DeepSeek V3.1 lists $0.27/1M input and $1/1M output tokens on the cheapest tracked provider. Compare the tier you will actually use; cheap async pricing can overstate savings for interactive workflows. 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 MIT. 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.
Continue comparing
Last reviewed: 2026-05-22. Data sourced from public model cards and provider documentation.