Claude Sonnet 4.5
ECI#61
147Claude Sonnet 4.5 is a closed-weights model from Anthropic, released September 29, 2025. It has an ECI score of 147 and ranks 61st of 249 tracked models. At the time of its release, it ranked 4th of 166 tracked models. At $3/Mtok for input tokens and $15/Mtok for output tokens, it is more expensive per token than similarly-capable models.
Input price$3 / 1M tokens
Output price$15 / 1M tokens
ParametersUnknown
Training computeUnknown
Claude Sonnet 4.5 vs select alternatives
Reasoning
| Domain | Benchmark | Claude Sonnet 4.5 | |||
|---|---|---|---|---|---|
ECI scoreBest score 166 | 147 | 144 | 150 | 146 | |
| Ranking | #61 | #83 | #47 | #66 | |
| Games | Chess PuzzlesBest score 72.0% | ||||
Earthborne Rangers (EBR-bench)Best score 76.2% | |||||
Mystery Game PuzzlesBest score 84.0% | |||||
| Mathematics | FrontierMath Tiers 1-3 (v2)Best score 93.7% | ||||
FrontierMath Tier 4 (v2)Best score 97.6% | |||||
OTIS Mock AIME 2024-2025Best score 100.0% | |||||
| Science | GPQA DiamondBest score 95.8% | ||||
| Software engineering | SWE-bench VerifiedBest score 83.5% | ||||
| World knowledge | SimpleQA VerifiedBest score 75.6% |
