Verdict
Claude Fable 5 leads 15–0 across 15 shared benchmarks.
Claude Fable 5 15 · Claude Opus 4.8 0 · higher isn't always better — check the caveats below.
Reported scores — protocols may differ. How we compare
Agentic: Claude Fable 5 leads 2–0 across 2 shared agentic benchmarks (largest gap: Remote Labor Index, 16.1 vs 8.33 — protocols undisclosed).
Coding: Claude Fable 5 leads 2–0 across 2 shared coding benchmarks (largest gap: CursorBench, 72.9 vs 63.8 — single evaluator).
Math: Claude Fable 5 leads 2–0 across 2 shared math benchmarks (largest gap: FrontierMath-Tier-4-v2-Private, 87.8 vs 56.1 — single evaluator).
Reasoning: Claude Fable 5 leads 2–0 across 2 shared reasoning benchmarks (largest gap: SimpleQA Verified, 68.3 vs 39.5 — single evaluator).
Unknown: Claude Fable 5 leads 2–0 across 2 shared unknown benchmarks (largest gap: EBR-bench, 31.75 vs 21.43 — single evaluator).
Vendor claims — compare against the measured scores above. A claim is what a developer says about its own model, not an independent measurement.
Agentic / Tool Use
“The longer and more complex the task, the larger Fable 5's lead over our other models”
Coding
“It is state-of-the-art on nearly all tested benchmarks of AI capability, showing exceptional performance in software engineering, knowledge work, vision, scientific research, and many other areas”
General
“Fable 5's capabilities exceed those of any model we've ever made generally available”
Multimodal
“It can extract precise numbers from detailed scientific figures and can perform complex vision-based tasks like rebuilding a web app's source code from screenshots alone”
No vendor claims on file for Claude Opus 4.8.
Claude Fable 5 leads 15–0 across 15 shared benchmarks. Claude Fable 5 leads 15 benchmarks and Claude Opus 4.8 leads 0. Higher isn't always better — see the integrity caveats on each benchmark.
Claude Fable 5 and Claude Opus 4.8 have 15 benchmarks in common in our data — those are the only rows where a direct, apples-to-apples comparison is drawn.
Claude Fable 5 leads agentic 2–0. Claude Fable 5 leads coding 2–0.