Verdict
Claude Opus 4.8 leads 15–4 across 19 shared benchmarks.
Claude Opus 4.6 4 · Claude Opus 4.8 15 · higher isn't always better — check the caveats below.
Reported scores — protocols may differ. How we compare
Reasoning: Claude Opus 4.6 leads 4–1 across 5 shared reasoning benchmarks (largest gap: SimpleQA Verified, 46.49 vs 39.5 — single evaluator).
Unknown: Claude Opus 4.8 leads 3–0 across 3 shared unknown benchmarks (largest gap: ProofBench, 69 vs 50 — single evaluator).
Agentic: Claude Opus 4.8 leads 2–0 across 2 shared agentic benchmarks (largest gap: APEX-Agents, 42.5 vs 32.4 — protocols undisclosed).
Math: Claude Opus 4.8 leads 2–0 across 2 shared math benchmarks (largest gap: FrontierMath-Tier-4-v2-Private, 56.1 vs 26.83 — 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.
Coding
“The new Claude Opus 4.6 improves on its predecessor's coding skills”
No vendor claims on file for Claude Opus 4.8.
Claude Opus 4.8 leads 15–4 across 19 shared benchmarks. Claude Opus 4.6 leads 4 benchmarks and Claude Opus 4.8 leads 15. Higher isn't always better — see the integrity caveats on each benchmark.
Claude Opus 4.6 and Claude Opus 4.8 have 19 benchmarks in common in our data — those are the only rows where a direct, apples-to-apples comparison is drawn.
Claude Opus 4.6 leads reasoning 4–1. Claude Opus 4.8 leads unknown 3–0.