GPT-5.5 Pro vs GPT-5 Pro
GPT-5.5 Pro Verdict
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 60.5.
- GPT-5.5 Pro (xhigh) is stronger in maths, reasoning.
- GPT-5 Pro is stronger in knowledge, multimodal.
- GPT-5 Pro is 1.6× cheaper ($41.25 vs $67.50 per 1M blended).
| Metric | GPT-5.5 Pro (xhigh) | GPT-5 Pro |
|---|---|---|
| BenchLeader Index | 67.1 | 60.5 |
| Maths score | 74.5 | – |
| Reasoning score | 80.1 | 57.6 |
| Knowledge score | – | 66.9 |
| Multimodal score | – | 67.4 |
| Blended price $/M | $67.50 | $41.25 |
| Output speed | 4 tok/s | – |
| Time to first answer | 3.5 s | – |
| Context window | 1.1M | 400k |
| FrontierMath Tiers 1–3 | 87.7% | – |
| FrontierMath Tier 4 | 78.0% | – |
| Humanity's Last Exam | – | 31.6% |
| SimpleBench | – | 61.6% |
| Epoch Capabilities Index | – | 150.3 |
| PRBench Finance | – | 51.1% |
| PRBench Legal | – | 49.9% |
| VISTA | – | 52.4% |
| MultiNRC | – | 65.2% |
| Kagi LLM Benchmark | – | 76.8% |
| ARC-AGI-1 | 95.0% | 70.2% |
| ARC-AGI-2 | 84.2% | 18.3% |
| CritPt | 30.6% | – |
| FORTRESS | – | 15.2% |
| MASK | – | 86.0% |
| LMCA | 53.9% | – |
| DTBench | 96.0% | – |
Data as of 2026-09-19. Best configuration of each model; every score links to its source on the model pages.
GPT-5.5 Pro vs GPT-5 Pro: questions
- Is GPT-5.5 Pro better than GPT-5 Pro?
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 60.5. 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, GPT-5.5 Pro or GPT-5 Pro?
- GPT-5 Pro is cheaper: $41.25 against $67.50 per million tokens, blended at three input tokens per output token.
- Which has the larger context window?
- GPT-5.5 Pro accepts more context: 1.1M against 400k tokens.