Verdict
GPT-5.5 leads 21–5 across 26 shared benchmarks.
Gemini 3.1 Pro 5 · GPT-5.5 21 · higher isn't always better — check the caveats below.
Reported scores — protocols may differ. How we compare
Unknown: GPT-5.5 leads 5–1 across 6 shared unknown benchmarks (largest gap: Mystery Game Puzzles, 51.53 vs 27.3 — protocols undisclosed).
Reasoning: Gemini 3.1 Pro leads 4–1 across 5 shared reasoning benchmarks (largest gap: SimpleBench, 75.52 vs 62.8 — single evaluator).
Coding: GPT-5.5 leads 3–0 across 3 shared coding benchmarks (largest gap: DeepSWE, 67.04 vs 11.73 — single evaluator).
Agentic: GPT-5.5 leads 2–0 across 2 shared agentic benchmarks (largest gap: ExploitBench, 47.4 vs 26.1 — protocols undisclosed).
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.
Agentic / Tool Use
“Gemini 3.1 Pro was evaluated across a range of benchmarks, including reasoning, multimodal capabilities, agentic tool use, multi-lingual performance, and long-context.”
Multimodal
“a suite of highly capable, natively multimodal reasoning models”
Reasoning
“Gemini 3.1 Pro is Google's most advanced model for complex tasks.”
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 21–5 across 26 shared benchmarks. Gemini 3.1 Pro leads 5 benchmarks and GPT-5.5 leads 21. Higher isn't always better — see the integrity caveats on each benchmark.
Gemini 3.1 Pro and GPT-5.5 have 26 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 5–1. Gemini 3.1 Pro leads reasoning 4–1.