Verdict
GPT-5.5 leads 11–6 across 17 shared benchmarks.
GPT-5.5 11 · Kimi K3 6 · higher isn't always better — check the caveats below.
Reported scores — protocols may differ. How we compare
Reasoning: GPT-5.5 leads 3–0 across 3 shared reasoning benchmarks (largest gap: SimpleQA Verified, 63.1 vs 42.7 — single evaluator).
Unknown: Kimi K3 leads 2–1 across 3 shared unknown benchmarks (largest gap: ProofBench, 87 vs 50 — single evaluator).
Coding: Kimi K3 leads 2–0 across 2 shared coding benchmarks (largest gap: DeepSWE, 68.51 vs 67.04 — single evaluator).
Math: GPT-5.5 leads 2–0 across 2 shared math benchmarks (largest gap: FrontierMath-Tier-4-v2-Private, 72.5 vs 39.02 — 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
“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.”
No vendor claims on file for Kimi K3.
GPT-5.5 leads 11–6 across 17 shared benchmarks. GPT-5.5 leads 11 benchmarks and Kimi K3 leads 6. Higher isn't always better — see the integrity caveats on each benchmark.
GPT-5.5 and Kimi K3 have 17 benchmarks in common in our data — those are the only rows where a direct, apples-to-apples comparison is drawn.
GPT-5.5 leads reasoning 3–0. Kimi K3 leads coding 2–0.