Verdict
Claude Sonnet 5.5 leads 6–5 across 13 shared benchmarks.
Claude Fable 5.1 5 · Claude Sonnet 5.5 6 · 2 tied · higher isn't always better — check the caveats below.
Reported scores — protocols may differ. How we compare
Unknown: Claude Sonnet 5.5 leads 2–1 across 4 shared unknown benchmarks (largest gap: Mystery Game Puzzles, 61.45 vs 53.73 — protocols undisclosed).
Coding: Claude Sonnet 5.5 leads 2–0 across 2 shared coding benchmarks (largest gap: FrontierSWE, 61.89 vs 56.29 — single evaluator).
Math: Claude Fable 5.1 leads 1–0 across 2 shared math benchmarks (largest gap: FrontierMath-Tier-4-v2-Private, 87.8 vs 80.49 — protocols undisclosed).
Reasoning: Claude Fable 5.1 leads 2–0 across 2 shared reasoning benchmarks (largest gap: SimpleQA Verified, 70.8 vs 46.5 — protocols undisclosed).
Claude Sonnet 5.5 leads 6–5 across 13 shared benchmarks. Claude Fable 5.1 leads 5 benchmarks and Claude Sonnet 5.5 leads 6, with 2 tied. Higher isn't always better — see the integrity caveats on each benchmark.
Claude Fable 5.1 and Claude Sonnet 5.5 have 13 benchmarks in common in our data — those are the only rows where a direct, apples-to-apples comparison is drawn.
Claude Sonnet 5.5 leads coding 2–0. Claude Fable 5.1 leads reasoning 2–0.