3 vs 0 benchmarks won
Anthropic Claude Sonnet 4.5 | OpenAI GPT-5.5-Pro | |
|---|---|---|
| Overview | ||
| Company | Anthropic | OpenAI |
| Release date | Sep 29 2025 | Apr 23 2026 |
| Model type | — | — |
| Open source | No | No |
| Specifications | ||
Parameters | — | — |
Context window | — | — |
| Benchmarks | ||
Science reasoning GPQA Diamond | 83.4% | — |
Software engineering SWE-Bench Verified | 77.2% | — |
Multimodal understanding MMMU | 68% | — |
| Timeline | ||
| Release gap | Claude Sonnet 4.5 shipped 206 days before GPT-5.5-Pro | |
Claude Sonnet 4.5 leads GPT-5.5-Pro on 3 of the tracked benchmarks (GPQA Diamond, SWE-Bench Verified, MMMU). Claude Sonnet 4.5 shipped 206 days before GPT-5.5-Pro, 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.
Direct benchmark comparisons are unavailable — at least one of these models has not published scores on GPQA Diamond, SWE-Bench Verified, or MMMU.