Across 40 shared benchmarks, Claude Fable 5.1 scores higher on 39 and Claude Sonnet 5 on 1. The widest gap is Terminal-Bench 4.0, where Claude Fable 5.1 scores 56 against 12.4. Claude Sonnet 5 is the cheaper of the two on tracked API pricing ($2.00 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 (direct, anthropic-official), otherwise the lowest tracked offer.