Across 20 shared benchmarks, Claude Fable 5.1 scores higher on 19 and Claude Sonnet 4 on 1. The widest gap is ARC-AGI-2, where Claude Fable 5.1 scores 90 against 13.6. Claude Sonnet 4 is the cheaper of the two on tracked API pricing ($3.00 against $10.00 per million input tokens).
Best tracked score per model per benchmark (default configuration; source-attributed). ↓ marks lower-is-better metrics. Open either model for its full surface, provenance and pricing. Quoted rates are the price-setter row we currently track for each model — its direct or vendor-official listing where one exists (anthropic-official, anthropic-official), otherwise the lowest tracked offer.