Claude Opus 5.5 vs GPT-5.5
Claude Opus 5.5 
GPT-5.5 Verdict
- Claude Opus 5.5 (thinking) leads on quality: 70.7 vs 67.2.
- Claude Opus 5.5 (thinking) is stronger in composite, knowledge, long context, multimodal, reasoning.
- GPT-5.5 (xhigh) is stronger in agents & tools, coding, instruction following, maths.
- Claude Opus 5.5 (thinking) is 1.4× cheaper ($8.00 vs $11.25 per 1M blended).
- GPT-5.5 (xhigh) streams 2.2× faster (108 vs 48 tokens per second).
| Metric | Claude Opus 5.5 (thinking) | GPT-5.5 (xhigh) |
|---|---|---|
| BenchLeader Index | 70.7 | 67.2 |
| Composite score | 95.0 | 71.4 |
| Knowledge score | 85.0 | 66.2 |
| Long context score | 68.5 | 68.4 |
| Multimodal score | 71.9 | 63.9 |
| Reasoning score | 95.0 | 78.8 |
| Agents & tools score | – | 61.9 |
| Coding score | – | 64.3 |
| Instruction following score | – | 73.8 |
| Maths score | – | 71.1 |
| Blended price $/M | $8.00 | $11.25 |
| Output speed | 48 tok/s | 108 tok/s |
| Time to first answer | 4.2 s | 72.5 s |
| Context window | 1M | 1.1M |
| FrontierMath Tiers 1–3 | – | 85.3% |
| FrontierMath Tier 4 | – | 72.5% |
| SimpleQA Verified | – | 63.0% |
| OSWorld-Verified 2.0 | – | 13.0% |
| SciCode | – | 56.1% |
| WeirdML | – | 84.9% |
| ProofBench | – | 50.0% |
| GSO-Bench | – | 40.2% |
| LMArena WebDev | – | 1510 |
| LMArena Agent | – | 5 |
| LiveBench | – | 80.2% |
| LiveBench Reasoning | – | 89.7% |
| LiveBench Coding | – | 82.2% |
| LiveBench Agentic Coding | – | 54.0% |
| LiveBench Mathematics | – | 95.9% |
| LiveBench Data Analysis | – | 81.6% |
| LiveBench Language | – | 87.4% |
| LiveBench Instruction Following | – | 70.7% |
| AA Intelligence Index | 57.6 | 38.4 |
| IFBench | – | 75.8% |
| AA-LCR | 84.7% | 84.3% |
| MMMU-Pro | 87.7% | 79.9% |
| AA-Omniscience | 46.4 | 20.5 |
| Terminal-Bench Hard | – | 60.6% |
| GPQA Diamond (AA) | – | 93.5% |
| Humanity's Last Exam (AA) | 61.4% | 45.8% |
| SciCode (AA) | 66.9% | 55.8% |
| τ²-Bench Telecom (AA) | – | 93.9% |
| LiveCodeBench | – | 85.3% |
| MMLU-Pro | – | 88.1% |
| LegalBench | – | 86.5% |
| CorpFin | – | 68.4% |
| TaxEval | – | 75.0% |
| SWE-bench (Vals) | – | 82.6% |
| GPQA Diamond (Vals) | – | 93.2% |
| Vals Index | – | 57.4 |
| AIME 2026 | – | 100.0% |
| HMMT February 2026 | – | 98.5% |
| MathArena Apex | – | 80.2% |
| MCP Atlas | – | 75.3% |
| ARC-AGI-1 | – | 95.0% |
| ARC-AGI-2 | – | 85.0% |
| CritPt | 31.7% | 27.1% |
| GDPval (AA) | 67.3% | 41.8% |
| τ²-Bench Banking (AA) | – | 39.0% |
| ITBench SRE (AA) | – | 45.8% |
| Analyst Agent (AA) | – | 50.0% |
| APEX-Agents (AA) | – | 37.7% |
| CaseLaw v2 | – | 66.2% |
| Code Migration | – | 45.2% |
| Excel Modeling Benchmark | – | 64.5% |
| Finance Agent v2 | – | 51.8% |
| Harvey's Legal Agent Benchmark | – | 3.8% |
| Legal Research Bench | – | 40.4% |
| MedCode | – | 49.1% |
| MedScribe | – | 86.9% |
| MMMU-Pro (Vals) | – | 88.3% |
| MortgageTax | – | 68.8% |
| ProgramBench | – | 0.5% |
| Public Benefits Bench | – | 60.9% |
| SAGE | – | 51.5% |
| SkillsBench | – | 62.2% |
| SREBench | – | 3.8% |
| Tax Agent Bench | – | 60.5% |
| Time Horizon Index: KSP | – | 8.3% |
| Vals Multimodal Index | – | 68.1% |
| Vibe Code Bench v1.1 | – | 69.8% |
| DrugDiscoveryBench | – | 51.6% |
| FORTRESS | – | 16.3% |
| SWE Atlas: Codebase QnA | – | 45.4% |
| SWE Atlas: Refactoring | – | 44.8% |
| SWE Atlas: Test Writing | – | 42.6% |
| EBR-bench | – | 34.3% |
| Mystery Game Puzzles | – | 56.0% |
| PostTrainBench | – | 27.2% |
| DeepSWE | – | 67.0% |
| LMCA | – | 54.3% |
| DTBench | – | 96.0% |
| ALE-Bench | – | 1943.0 |
| GDP.pdf | – | 26.0% |
| Terminal-Bench 4.0 (AA) | 59.6% | 14.7% |
| Terminal-Bench 2.1 (AA) | – | 84.3% |
| AutomationBench | 69.5% | – |
| GDP.pdf | 26.2% | – |
| Harvey LAB | 91.2% | – |
| AA-Omniscience: accuracy | 66.2% | 58.0% |
| AA-Omniscience: non-hallucination | 41.4% | 11.0% |
| 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 GPT-5.5: questions
- Is Claude Opus 5.5 better than GPT-5.5?
- Claude Opus 5.5 (thinking) leads on quality: 70.7 vs 67.2. 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 GPT-5.5?
- Claude Opus 5.5 is cheaper: $8.00 against $11.25 per million tokens, blended at three input tokens per output token.
- Which is faster, Claude Opus 5.5 or GPT-5.5?
- GPT-5.5 streams faster: 108 against 48 output tokens per second.
- Which has the larger context window?
- GPT-5.5 accepts more context: 1.1M against 1M tokens.