Claude Sonnet 4.5
ECI#66
147Claude Sonnet 4.5 is a closed-weights model from Anthropic, released September 29, 2025. It has an ECI score of 147 and ranks 66th of 253 tracked models. At the time of its release, it ranked 4th of 166 tracked models.
Claude Sonnet 4.5 vs select alternatives
| Domain | Benchmark | Claude Sonnet 4.5 | |||
|---|---|---|---|---|---|
ECI scoreBest score 167 | 147 | 144 | 150 | 146 | |
| Ranking | #66 | #88 | #51 | #71 | |
| Games | Chess PuzzlesBest score 72% | ||||
Earthborne Rangers (EBR-bench)Best score 76% | |||||
Mystery Game PuzzlesBest score 84% | |||||
| Mathematics | FrontierMath Tiers 1-3 (v2)Best score 94% | ||||
FrontierMath Tier 4 (v2)Best score 100% | |||||
OTIS Mock AIME 2024-2025Best score 100% | |||||
| Science | GPQA DiamondBest score 96% | ||||
| Software engineering | SWE-bench VerifiedBest score 83% | ||||
| World knowledge | SimpleQA VerifiedBest score 76% |
