Claude Sonnet 5.5 vs DeepSeek V4.1 Flash
A direct, empirical evaluation of Claude Sonnet 5.5 (Anthropic) against DeepSeek V4.1 Flash (DeepSeek-AI).
Claude Sonnet 5.5
Developed by Anthropic · Proprietary Frontier Dynamic Hybrid Reasoner parameters
Terminal-Bench 4.0 execution (70.6%), SWE-bench Verified coding (82.4%), GitHub Copilot multi-file edits, and low-latency autonomous agentic coding at $2/$10 pricing.
DeepSeek V4.1 Flash
Developed by DeepSeek-AI · 552B parameters
High-throughput software engineering, autonomous coding loops, terminal agents, 1M long-context retrieval, and low-cost production inference.
| Metric | Claude Sonnet 5.5 | DeepSeek V4.1 Flash |
|---|---|---|
| SWE-bench Verified | 82.4% | 67.2% |
| MMLU-Pro | 88.4% | 78.4% |
| MATH-500 | 95.2% | 92.6% |
| Context Window | 1,000,000 tokens | 1,000,000 tokens |
| Input Pricing (per 1M) | $2.00 | $0.06 |
| Output Pricing (per 1M) | $10.00 | $0.22 |