Claude Fable 5.1
ECI#6
166Claude Fable 5.1 is a closed-weights model from Anthropic, released September 1, 2026. It has an ECI score of 166 and ranks 6th of 254 tracked models. At the time of its release, it ranked 1st of 236 tracked models.
Claude Fable 5.1 vs select alternatives
| Domain | Benchmark | Claude Fable 5.1 | |||
|---|---|---|---|---|---|
ECI scoreBest score 169 | 166 | 164 | 163 | 158 | |
| Ranking | #6 | #8 | #10 | #20 | |
| Games | Chess PuzzlesBest score 76% | ||||
Earthborne Rangers (EBR-bench)Best score 78% | |||||
Mystery Game PuzzlesBest score 84% | |||||
| Mathematics | FrontierMath ErdősBest score 4% | ||||
FrontierMath Tiers 1-3 (v2)Best score 94% | |||||
FrontierMath Tier 4 (v2)Best score 100% | |||||
OTIS Mock AIME 2024-2025Best score 100% | |||||
| Multimodal | Furniture Assembly BenchmarkBest score 83% | ||||
| World knowledge | SimpleQA VerifiedBest score 76% |
