Verdict
GPT-6.1 Sol leads 8–5 across 15 shared benchmarks.
Claude Opus 5.5 5 · GPT-6.1 Sol 8 · 2 tied · higher isn't always better — check the caveats below.
Reported scores — protocols may differ. How we compare
Unknown: Claude Opus 5.5 leads 3–2 across 5 shared unknown benchmarks (largest gap: SpireClimb, 24.67 vs 3.33 — protocols undisclosed).
Reasoning: GPT-6.1 Sol leads 2–0 across 3 shared reasoning benchmarks (largest gap: GPQA diamond, 93.86 vs 87.46 — protocols undisclosed).
Math: GPT-6.1 Sol leads 1–0 across 2 shared math benchmarks (largest gap: FrontierMath-Tier-4-v2-Private, 100 vs 95 — protocols undisclosed).
GPT-6.1 Sol leads 8–5 across 15 shared benchmarks. Claude Opus 5.5 leads 5 benchmarks and GPT-6.1 Sol leads 8, with 2 tied. Higher isn't always better — see the integrity caveats on each benchmark.
Claude Opus 5.5 and GPT-6.1 Sol have 15 benchmarks in common in our data — those are the only rows where a direct, apples-to-apples comparison is drawn.
GPT-6.1 Sol leads reasoning 2–0. Claude Opus 5.5 leads unknown 3–2.