Claude Opus 4.8 vs GPT-5.5 Pro
Claude Opus 4.8 
GPT-5.5 Pro Verdict
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 64.2.
- Claude Opus 4.8 (max) is stronger in agents & tools, coding, composite, instruction following, knowledge, long context.
- GPT-5.5 Pro (xhigh) is stronger in maths, reasoning.
- Claude Opus 4.8 (max) is 6.8× cheaper ($10.00 vs $67.50 per 1M blended).
- Claude Opus 4.8 (max) streams 13.4× faster (54 vs 4 tokens per second).
| Metric | Claude Opus 4.8 (max) | GPT-5.5 Pro (xhigh) |
|---|---|---|
| BenchLeader Index | 64.2 | 67.1 |
| Agents & tools score | 58.8 | – |
| Coding score | 62.5 | – |
| Composite score | 68.7 | – |
| Instruction following score | 62.0 | – |
| Knowledge score | 69.3 | – |
| Long context score | 65.2 | – |
| Maths score | 69.6 | 74.5 |
| Reasoning score | 72.1 | 80.1 |
| Blended price $/M | $10.00 | $67.50 |
| Output speed | 54 tok/s | 4 tok/s |
| Time to first answer | 24.0 s | 3.5 s |
| Context window | 1M | 1.1M |
| GPQA Diamond | 91.0% | – |
| FrontierMath Tiers 1–3 | 80.0% | 87.7% |
| FrontierMath Tier 4 | 56.1% | 78.0% |
| OTIS Mock AIME | 98.3% | – |
| SimpleQA Verified | 53.0% | – |
| Terminal-Bench | 23.6% | – |
| OSWorld-Verified 2.0 | 20.6% | – |
| SciCode | 53.5% | – |
| APEX-Agents | 42.5% | – |
| ProofBench | 69.0% | – |
| LiveBench | 76.2% | – |
| LiveBench Reasoning | 89.2% | – |
| LiveBench Coding | 81.8% | – |
| LiveBench Agentic Coding | 50.5% | – |
| LiveBench Mathematics | 94.3% | – |
| LiveBench Data Analysis | 66.0% | – |
| LiveBench Language | 79.7% | – |
| LiveBench Instruction Following | 72.0% | – |
| AA Intelligence Index | 42.0 | – |
| IFBench | 62.2% | – |
| AA-LCR | 77.7% | – |
| AA-Omniscience | 28.8 | – |
| Terminal-Bench Hard | 58.3% | – |
| GPQA Diamond (AA) | 92.0% | – |
| Humanity's Last Exam (AA) | 48.7% | – |
| SciCode (AA) | 54.4% | – |
| τ²-Bench Telecom (AA) | 94.4% | – |
| AIME 2026 | 100.0% | – |
| HMMT February 2026 | 95.5% | – |
| MathArena Apex | 81.3% | – |
| MCP Atlas | 82.2% | – |
| ARC-AGI-1 | 92.5% | 95.0% |
| ARC-AGI-2 | – | 84.2% |
| CritPt | 20.9% | 30.6% |
| GDPval (AA) | 49.5% | – |
| τ²-Bench Banking (AA) | 34.2% | – |
| Analyst Agent (AA) | 45.0% | – |
| DrugDiscoveryBench | 46.8% | – |
| FORTRESS | 18.2% | – |
| Chess Puzzles | 34.0% | – |
| EBR-bench | 28.6% | – |
| Mystery Game Puzzles | 36.0% | – |
| PostTrainBench | 32.9% | – |
| DeepSWE | 59.0% | – |
| LMCA | 57.5% | 53.9% |
| DTBench | 94.9% | 96.0% |
| CursorBench | 62.3% | – |
| Vending-Bench 2 | 2992.3 | – |
| GDP.pdf | 24.0% | – |
Data as of 2026-09-19. Best configuration of each model; every score links to its source on the model pages.
Claude Opus 4.8 vs GPT-5.5 Pro: questions
- Is Claude Opus 4.8 better than GPT-5.5 Pro?
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 64.2. 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 Opus 4.8 or GPT-5.5 Pro?
- Claude Opus 4.8 is cheaper: $10.00 against $67.50 per million tokens, blended at three input tokens per output token.
- Which is faster, Claude Opus 4.8 or GPT-5.5 Pro?
- Claude Opus 4.8 streams faster: 54 against 4 output tokens per second.
- Which has the larger context window?
- GPT-5.5 Pro accepts more context: 1.1M against 1M tokens.