Claude Sonnet 4.5
ECI#80
148Claude Sonnet 4.5 is a closed-weights model from Anthropic, released September 29, 2025. It has an ECI score of 148 and ranks 80th of 240 tracked models. At the time of its release, it ranked 2nd of 142 tracked models.
Claude Sonnet 4.5 vs select alternatives
| Domain | Benchmark | Claude Sonnet 4.5 | |||
|---|---|---|---|---|---|
ECI scoreBest score 173 | 148 | 145 | 150 | 147 | |
| Ranking | #80 | #97 | #70 | #85 | |
| Games | Chess PuzzlesBest score 79% | ||||
Mystery Game PuzzlesBest score 90% | |||||
Earthborne Rangers (EBR-bench)Best score 90% | |||||
| Mathematics | FrontierMath Tiers 1-3 (v2)Best score 95% | ||||
FrontierMath Tier 4 (v2)Best score 100% | |||||
OTIS Mock AIME 2024-2025Best score 100% | |||||
| Science | GPQA DiamondBest score 97% | ||||
| Software engineering | SWE-bench VerifiedBest score 83% | ||||
| World knowledge | SimpleQA VerifiedBest score 94% |
