1 vs 1 benchmarks won
Anthropic Claude Opus 4.5 | OpenAI GPT-5.5 | |
|---|---|---|
| Overview | ||
| Company | Anthropic | OpenAI |
| Release date | Nov 24 2025 | Apr 23 2026 |
| Model type | — | — |
| Open source | No | No |
| Specifications | ||
Parameters | — | — |
Context window | — | — |
| Benchmarks | ||
Science reasoning GPQA Diamond | 87% | 93.6% |
Software engineering SWE-Bench Verified | 80.9% | — |
Multimodal understanding MMMU | — | — |
| Timeline | ||
| Release gap | Claude Opus 4.5 shipped 150 days before GPT-5.5 | |
Claude Opus 4.5 and GPT-5.5 are evenly matched across the benchmarks they both publish. Claude Opus 4.5 shipped 150 days before GPT-5.5, so benchmark comparisons should account for the intervening progress.
Published specifications for these two models are limited — see each model page for the latest details.
On GPQA Diamond, GPT-5.5 scores 93.6%, 6.6 points above Claude Opus 4.5 at 87%.