Claude Opus 5.5 vs DeepSeek V4 Flash
Claude Opus 5.5 
DeepSeek V4 Flash Verdict
- Claude Opus 5.5 (thinking) leads on quality: 70.7 vs 61.6.
- Claude Opus 5.5 (thinking) is stronger in composite, knowledge, long context, multimodal, reasoning.
- DeepSeek V4 Flash (max) is stronger in agents & tools, coding, instruction following, maths.
- DeepSeek V4 Flash (max) is 31× cheaper ($0.262 vs $8.00 per 1M blended).
- DeepSeek V4 Flash (max) streams 4.6× faster (221 vs 48 tokens per second).
| Metric | Claude Opus 5.5 (thinking) | DeepSeek V4 Flash (max) |
|---|---|---|
| BenchLeader Index | 70.7 | 61.6 |
| Composite score | 95.0 | 71.1 |
| Knowledge score | 85.0 | 56.7 |
| Long context score | 68.5 | 66.0 |
| Multimodal score | 71.9 | – |
| Reasoning score | 95.0 | 72.1 |
| Agents & tools score | – | 67.0 |
| Coding score | – | 48.6 |
| Instruction following score | – | 76.7 |
| Maths score | – | 57.3 |
| Blended price $/M | $8.00 | $0.262 |
| Output speed | 48 tok/s | 221 tok/s |
| Time to first answer | 4.2 s | 10.2 s |
| Context window | 1M | 1M |
| SciCode | – | 44.9% |
| WeirdML | – | 45.6% |
| AA Intelligence Index | 57.6 | 34.3 |
| IFBench | – | 79.2% |
| AA-LCR | 84.7% | 79.7% |
| MMMU-Pro | 87.7% | – |
| AA-Omniscience | 46.4 | -14.3 |
| Terminal-Bench Hard | – | 35.6% |
| GPQA Diamond (AA) | – | 90.8% |
| Humanity's Last Exam (AA) | 61.4% | 38.5% |
| SciCode (AA) | 66.9% | 50.4% |
| τ²-Bench Telecom (AA) | – | 95.0% |
| AIME 2026 | – | 95.8% |
| HMMT February 2026 | – | 93.9% |
| MathArena Apex | – | 27.1% |
| CritPt | 31.7% | 16.6% |
| GDPval (AA) | 67.3% | 46.3% |
| τ²-Bench Banking (AA) | – | 39.4% |
| ITBench SRE (AA) | – | 31.5% |
| Analyst Agent (AA) | – | 25.0% |
| LMCA | – | 35.9% |
| DTBench | – | 86.4% |
| Terminal-Bench 4.0 (AA) | 59.6% | 12.1% |
| Terminal-Bench 2.1 (AA) | – | 78.7% |
| AutomationBench | 69.5% | – |
| GDP.pdf | 26.2% | – |
| Harvey LAB | 91.2% | – |
| AA-Omniscience: accuracy | 66.2% | 40.4% |
| AA-Omniscience: non-hallucination | 41.4% | 8.3% |
| AA-Briefcase | 1822 | – |
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 Flash: questions
- Is Claude Opus 5.5 better than DeepSeek V4 Flash?
- Claude Opus 5.5 (thinking) leads on quality: 70.7 vs 61.6. 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 Flash?
- DeepSeek V4 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 Flash?
- DeepSeek V4 Flash streams faster: 221 against 48 output tokens per second.
- Which has the larger context window?
- Both accept 1M tokens of context.