Verdict
GPT-6 Astra leads 6–0 across 7 shared benchmarks.
GPT-5.5 Pro 0 · GPT-6 Astra 6 · 1 tied · higher isn't always better — check the caveats below.
Reported scores — protocols may differ. How we compare
Math: GPT-6 Astra leads 1–0 across 2 shared math benchmarks (largest gap: FrontierMath-Tier-4-v2-Private, 97.6 vs 78.05 — protocols undisclosed).
Reasoning: GPT-6 Astra leads 2–0 across 2 shared reasoning benchmarks (largest gap: GPQA diamond, 94.36 vs 91.9 — protocols undisclosed).
Vendor claims — compare against the measured scores above. A claim is what a developer says about its own model, not an independent measurement.
General
“In GPT-5.5 Pro, early testers are seeing a significant step up in both the difficulty and quality of work ChatGPT can take on”
Reasoning
“GPT-5.5 Pro, designed for even harder questions and higher-accuracy work, is available to Pro, Business, and Enterprise users.”
Writing
“testers found GPT-5.5 Pro's responses significantly more comprehensive, well-structured, accurate, relevant, and useful”
No vendor claims on file for GPT-6 Astra.
GPT-6 Astra leads 6–0 across 7 shared benchmarks. GPT-5.5 Pro leads 0 benchmarks and GPT-6 Astra leads 6, with 1 tied. Higher isn't always better — see the integrity caveats on each benchmark.
GPT-5.5 Pro and GPT-6 Astra have 7 benchmarks in common in our data — those are the only rows where a direct, apples-to-apples comparison is drawn.
GPT-6 Astra leads reasoning 2–0. GPT-6 Astra leads math 1–0.