Verdict
GPT-5.5 leads 17–2 across 19 shared benchmarks.
Gemini 3.5 Flash 2 · GPT-5.5 17 · higher isn't always better — check the caveats below.
Reported scores — protocols may differ. How we compare
Unknown: GPT-5.5 leads 6–0 across 6 shared unknown benchmarks (largest gap: Surface Evolver Bench, 88.12 vs 58.13 — single evaluator).
Reasoning: Evenly split 2–2 across 4 shared reasoning benchmarks (largest gap: SimpleBench, 72.04 vs 62.8 — single evaluator).
Math: GPT-5.5 leads 2–0 across 2 shared math benchmarks (largest gap: FrontierMath-Tier-4-v2-Private, 72.5 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.
No vendor claims on file for Gemini 3.5 Flash.
Agentic / Tool Use
“The gains are especially strong in agentic coding, computer use, knowledge work, and early scientific research”
Coding
“It excels at writing and debugging code, researching online, analyzing data, creating documents and spreadsheets, operating software, and moving across tools until a task is finished.”
General
“We're releasing GPT-5.5, our smartest and most intuitive to use model yet, and the next step toward a new way of getting work done on a computer.”
Speed / Latency
“GPT-5.5 matches GPT-5.4 per-token latency in real-world serving, while performing at a much higher level of intelligence.”
GPT-5.5 leads 17–2 across 19 shared benchmarks. Gemini 3.5 Flash leads 2 benchmarks and GPT-5.5 leads 17. Higher isn't always better — see the integrity caveats on each benchmark.
Gemini 3.5 Flash and GPT-5.5 have 19 benchmarks in common in our data — those are the only rows where a direct, apples-to-apples comparison is drawn.
GPT-5.5 leads unknown 6–0. GPT-5.5 leads math 2–0.