Claude Sonnet 5 vs GPT-5.5 Pro
Claude Sonnet 5 
GPT-5.5 Pro Verdict
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 62.2.
- Claude Sonnet 5 (high) is stronger in agents & tools, coding, composite, human preference, knowledge, long context, multimodal.
- GPT-5.5 Pro (xhigh) is stronger in maths, reasoning.
- Claude Sonnet 5 (high) is 17× cheaper ($4.00 vs $67.50 per 1M blended).
- Claude Sonnet 5 (high) streams 16.1× faster (64 vs 4 tokens per second).
| Metric | Claude Sonnet 5 (high) | GPT-5.5 Pro (xhigh) |
|---|---|---|
| BenchLeader Index | 62.2 | 67.1 |
| Agents & tools score | 62.0 | – |
| Coding score | 61.5 | – |
| Composite score | 69.6 | – |
| Human preference score | 65.9 | – |
| Knowledge score | 62.4 | – |
| Long context score | 64.7 | – |
| Maths score | 66.9 | 74.5 |
| Multimodal score | 62.6 | – |
| Reasoning score | 69.6 | 80.1 |
| Blended price $/M | $4.00 | $67.50 |
| Output speed | 64 tok/s | 4 tok/s |
| Time to first answer | 2.9 s | 3.5 s |
| Context window | 1M | 1.1M |
| FrontierMath Tiers 1–3 | – | 87.7% |
| FrontierMath Tier 4 | – | 78.0% |
| 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 | 32.0 | – |
| AA-LCR | 76.7% | – |
| AA-Omniscience | -3.7 | – |
| Humanity's Last Exam (AA) | 35.7% | – |
| SciCode (AA) | 54.3% | – |
| ARC-AGI-1 | – | 95.0% |
| ARC-AGI-2 | – | 84.2% |
| CritPt | 15.1% | 30.6% |
| GDPval (AA) | 40.4% | – |
| 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 | – | 53.9% |
| DTBench | – | 96.0% |
| CursorBench | 56.9% | – |
| ALE-Bench | 1463.1 | – |
Data as of 2026-09-19. Best configuration of each model; every score links to its source on the model pages.
Claude Sonnet 5 vs GPT-5.5 Pro: questions
- Is Claude Sonnet 5 better than GPT-5.5 Pro?
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 62.2. The BenchLeader Index combines every independent quality benchmark; GPT-5.5 Pro (xhigh) is ahead overall as of 2026-09-19, but check the category scores for your use.
- Which is cheaper, Claude Sonnet 5 or GPT-5.5 Pro?
- Claude Sonnet 5 is cheaper: $4.00 against $67.50 per million tokens, blended at three input tokens per output token.
- Which is faster, Claude Sonnet 5 or GPT-5.5 Pro?
- Claude Sonnet 5 streams faster: 64 against 4 output tokens per second.
- Which has the larger context window?
- GPT-5.5 Pro accepts more context: 1.1M against 1M tokens.