Claude Opus 5.5 vs Claude Sonnet 5
Claude Opus 5.5 Verdict
- Claude Opus 5.5 (thinking) leads on quality: 70.7 vs 61.8.
- Claude Opus 5.5 (thinking) is stronger in composite, knowledge, long context, multimodal, reasoning.
- Claude Sonnet 5 (high) is stronger in agents & tools, coding, human preference, maths.
- Claude Sonnet 5 (high) is 2.0× cheaper ($4.00 vs $8.00 per 1M blended).
- Claude Sonnet 5 (high) streams 1.4× faster (69 vs 48 tokens per second).
| Metric | Claude Opus 5.5 (thinking) | Claude Sonnet 5 (high) |
|---|---|---|
| BenchLeader Index | 70.7 | 61.8 |
| Composite score | 95.0 | 67.8 |
| Knowledge score | 85.0 | 61.6 |
| Long context score | 68.5 | 64.4 |
| Multimodal score | 71.9 | 62.6 |
| Reasoning score | 95.0 | 68.5 |
| Agents & tools score | – | 62.0 |
| Coding score | – | 61.2 |
| Human preference score | – | 65.9 |
| Maths score | – | 66.9 |
| Blended price $/M | $8.00 | $4.00 |
| Output speed | 48 tok/s | 69 tok/s |
| Time to first answer | 4.2 s | 11.7 s |
| Context window | 1M | 1M |
| SciCode | – | 48.6% |
| WeirdML | – | 68.8% |
| LMArena Text | – | 1461 |
| LMArena Hard Prompts | – | 1489 |
| LMArena Coding | – | 1521 |
| LMArena WebDev | – | 1537 |
| LMArena Vision | – | 1277 |
| LMArena Agent | – | 6 |
| AA Intelligence Index | 57.6 | 31.7 |
| AA-LCR | 84.7% | 76.7% |
| MMMU-Pro | 87.7% | – |
| AA-Omniscience | 46.4 | -3.7 |
| Humanity's Last Exam (AA) | 61.4% | 35.7% |
| SciCode (AA) | 66.9% | 54.3% |
| CritPt | 31.7% | 15.1% |
| GDPval (AA) | 67.3% | 37.3% |
| LMArena Maths | – | 1476 |
| LMArena Creative Writing | – | 1437 |
| LMArena Instruction Following | – | 1465 |
| LMArena Multi-turn | – | 1473 |
| LMArena Longer Queries | – | 1482 |
| LMArena Document | – | 1476 |
| DeepSWE | – | 48.2% |
| LMCA | – | 50.0% |
| DTBench | – | 84.5% |
| CursorBench | – | 30.8% |
| ALE-Bench | – | 1463.1 |
| Terminal-Bench 4.0 (AA) | 59.6% | 5.0% |
| AutomationBench | 69.5% | – |
| GDP.pdf | 26.2% | – |
| Harvey LAB | 91.2% | – |
| AA-Omniscience: accuracy | 66.2% | 37.4% |
| AA-Omniscience: non-hallucination | 41.4% | 34.3% |
| 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 Claude Sonnet 5: questions
- Is Claude Opus 5.5 better than Claude Sonnet 5?
- Claude Opus 5.5 (thinking) leads on quality: 70.7 vs 61.8. 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 Claude Sonnet 5?
- Claude Sonnet 5 is cheaper: $4.00 against $8.00 per million tokens, blended at three input tokens per output token.
- Which is faster, Claude Opus 5.5 or Claude Sonnet 5?
- Claude Sonnet 5 streams faster: 69 against 48 output tokens per second.
- Which has the larger context window?
- Both accept 1M tokens of context.