Claude Sonnet 4.5
Anthropic's latest mid-size model, part of the Claude 4.5 series.
Anthropic
2025-09-30
Closed weightsRank: 18/160146Epoch Capabilities Index
About ECI90% CI: 144-148
Reasoning
Claude Sonnet 4.5 performance
Top performing model
Anthropic's latest mid-size model, part of the Claude 4.5 series.
Anthropic2025-09-30Closed weights