GPT-5.5 Pro vs GPT-6 Luna
GPT-5.5 Pro Verdict
- GPT-5.5 Pro (xhigh) leads on quality: 67.0 vs 61.2.
- GPT-5.5 Pro (xhigh) is stronger in maths, reasoning.
- GPT-6 Luna (max) is stronger in composite, knowledge, long context, multimodal.
- GPT-6 Luna (max) is 338× cheaper ($0.200 vs $67.50 per 1M blended).
- GPT-6 Luna (max) streams 39.3× faster (157 vs 4 tokens per second).
| Metric | GPT-5.5 Pro (xhigh) | GPT-6 Luna (max) |
|---|---|---|
| BenchLeader Index | 67.0 | 61.2 |
| Maths score | 74.3 | – |
| Reasoning score | 80.1 | 76.1 |
| Composite score | – | 73.9 |
| Knowledge score | – | 63.2 |
| Long context score | – | 67.5 |
| Multimodal score | – | 59.2 |
| Blended price $/M | $67.50 | $0.200 |
| Output speed | 4 tok/s | 157 tok/s |
| Time to first answer | 3.4 s | 142.6 s |
| Context window | 1.1M | 1.1M |
| FrontierMath Tiers 1–3 | 87.7% | – |
| FrontierMath Tier 4 | 78.0% | – |
| AA Intelligence Index | – | 37.3 |
| AA-LCR | – | 83.3% |
| MMMU-Pro | – | 75.5% |
| AA-Omniscience | – | 0.7 |
| Humanity's Last Exam (AA) | – | 38.5% |
| SciCode (AA) | – | 54.6% |
| ARC-AGI-1 | 95.0% | – |
| ARC-AGI-2 | 84.2% | – |
| CritPt | 30.6% | 19.4% |
| GDPval (AA) | – | 43.4% |
| LMCA | 53.9% | – |
| DTBench | 96.0% | – |
| Terminal-Bench 4.0 (AA) | – | 12.6% |
| AutomationBench | – | 53.2% |
| GDP.pdf | – | 20.4% |
| MLCR | – | 16.1% |
| AA-Omniscience: accuracy | – | 43.8% |
| AA-Omniscience: non-hallucination | – | 23.3% |
| AA-Briefcase | – | 1299 |
Data as of 2026-09-23. Best configuration of each model; every score links to its source on the model pages.
GPT-5.5 Pro vs GPT-6 Luna: questions
- Is GPT-5.5 Pro better than GPT-6 Luna?
- GPT-5.5 Pro (xhigh) leads on quality: 67.0 vs 61.2. The BenchLeader Index combines every independent quality benchmark; GPT-5.5 Pro (xhigh) is ahead overall as of 2026-09-23, but check the category scores for your use.
- Which is cheaper, GPT-5.5 Pro or GPT-6 Luna?
- GPT-6 Luna is cheaper: $0.200 against $67.50 per million tokens, blended at three input tokens per output token.
- Which is faster, GPT-5.5 Pro or GPT-6 Luna?
- GPT-6 Luna streams faster: 157 against 4 output tokens per second.
- Which has the larger context window?
- Both accept 1.1M tokens of context.