3 vs 0 benchmarks won
Anthropic Claude Sonnet 4.5 | xAI Grok 4 Fast | |
|---|---|---|
| Overview | ||
| Company | Anthropic | xAI |
| Release date | Sep 29 2025 | Sep 2025 |
| 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 | Grok 4 Fast shipped 28 days before Claude Sonnet 4.5 | |
Claude Sonnet 4.5 leads Grok 4 Fast on 3 of the tracked benchmarks (GPQA Diamond, SWE-Bench Verified, MMMU). Grok 4 Fast shipped 28 days before Claude Sonnet 4.5, 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.
Direct benchmark comparisons are unavailable — at least one of these models has not published scores on GPQA Diamond, SWE-Bench Verified, or MMMU.