Verdict
Gemini 3.5 Flash leads 9–7 across 17 shared benchmarks.
Claude Opus 4.6 7 · Gemini 3.5 Flash 9 · 1 tied · higher isn't always better — check the caveats below.
Reported scores — protocols may differ. How we compare
Unknown: Claude Opus 4.6 leads 3–2 across 5 shared unknown benchmarks (largest gap: ProofBench, 50 vs 31 — single evaluator).
Reasoning: Gemini 3.5 Flash leads 3–1 across 4 shared reasoning benchmarks (largest gap: SimpleQA Verified, 66.2 vs 47 — protocols undisclosed).
Math: Gemini 3.5 Flash leads 1–0 across 2 shared math benchmarks (largest gap: OTIS Mock AIME 2024-2025, 95.55 vs 94.44 — 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 Gemini 3.5 Flash.
Gemini 3.5 Flash leads 9–7 across 17 shared benchmarks. Claude Opus 4.6 leads 7 benchmarks and Gemini 3.5 Flash leads 9, with 1 tied. Higher isn't always better — see the integrity caveats on each benchmark.
Claude Opus 4.6 and Gemini 3.5 Flash have 17 benchmarks in common in our data — those are the only rows where a direct, apples-to-apples comparison is drawn.
Gemini 3.5 Flash leads reasoning 3–1. Claude Opus 4.6 leads unknown 3–2.