Claude Opus 5.5 vs DeepSeek V4.1 Flash
Claude Opus 5.5 
DeepSeek V4.1 Flash Verdict
- Claude Opus 5.5 (thinking) leads on quality: 70.7 vs 61.4.
- Claude Opus 5.5 (thinking) is stronger in composite, knowledge, long context, multimodal, reasoning.
- DeepSeek V4.1 Flash (max) is stronger in agents & tools, coding.
- DeepSeek V4.1 Flash (max) is 31× cheaper ($0.262 vs $8.00 per 1M blended).
- DeepSeek V4.1 Flash (max) streams 4.6× faster (219 vs 48 tokens per second).
| Metric | Claude Opus 5.5 (thinking) | DeepSeek V4.1 Flash (max) |
|---|---|---|
| BenchLeader Index | 70.7 | 61.4 |
| Composite score | 95.0 | 73.4 |
| Knowledge score | 85.0 | 60.9 |
| Long context score | 68.5 | 68.2 |
| Multimodal score | 71.9 | 60.9 |
| Reasoning score | 95.0 | 67.9 |
| Agents & tools score | – | 59.6 |
| Coding score | – | 65.7 |
| Blended price $/M | $8.00 | $0.262 |
| Output speed | 48 tok/s | 219 tok/s |
| Time to first answer | 4.2 s | 10.1 s |
| Context window | 1M | 1M |
| SciCode | – | 51.9% |
| LMArena WebDev | – | 1614 |
| LMArena Agent | – | 4.9 |
| LiveBench | – | 81.1% |
| LiveBench Reasoning | – | 86.7% |
| LiveBench Coding | – | 80.0% |
| LiveBench Agentic Coding | – | 77.3% |
| LiveBench Mathematics | – | 93.3% |
| LiveBench Data Analysis | – | 79.3% |
| LiveBench Language | – | 81.2% |
| LiveBench Instruction Following | – | 70.0% |
| AA Intelligence Index | 57.6 | 39.5 |
| AA-LCR | 84.7% | 84.0% |
| MMMU-Pro | 87.7% | 77.0% |
| AA-Omniscience | 46.4 | -5.3 |
| Humanity's Last Exam (AA) | 61.4% | 39.3% |
| SciCode (AA) | 66.9% | 51.9% |
| CritPt | 31.7% | 14.3% |
| GDPval (AA) | 67.3% | 55.0% |
| ALE-Bench | – | 1092.3 |
| Terminal-Bench 4.0 (AA) | 59.6% | 26.8% |
| AutomationBench | 69.5% | 68.9% |
| GDP.pdf | 26.2% | 12.8% |
| MLCR | – | 22.8% |
| Harvey LAB | 91.2% | – |
| AA-Omniscience: accuracy | 66.2% | 46.4% |
| AA-Omniscience: non-hallucination | 41.4% | 3.5% |
| AA-Briefcase | 1822 | 1432 |
| AA Openness Index | – | 44.4 |
Data as of 2026-09-22. Best configuration of each model; every score links to its source on the model pages.
Claude Opus 5.5 vs DeepSeek V4.1 Flash: questions
- Is Claude Opus 5.5 better than DeepSeek V4.1 Flash?
- Claude Opus 5.5 (thinking) leads on quality: 70.7 vs 61.4. The BenchLeader Index combines every independent quality benchmark; Claude Opus 5.5 (thinking) is ahead overall as of 2026-09-22, but check the category scores for your use.
- Which is cheaper, Claude Opus 5.5 or DeepSeek V4.1 Flash?
- DeepSeek V4.1 Flash is cheaper: $0.262 against $8.00 per million tokens, blended at three input tokens per output token.
- Which is faster, Claude Opus 5.5 or DeepSeek V4.1 Flash?
- DeepSeek V4.1 Flash streams faster: 219 against 48 output tokens per second.
- Which has the larger context window?
- Both accept 1M tokens of context.