Side-by-side benchmark comparison across knowledge, coding, math, and reasoning.
GPT-5.1-Codex-Max is clearly ahead on the aggregate, 87 to 31. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.1-Codex-Max's sharpest advantage is in mathematics, where it averages 96.6 against 85.2. The single biggest benchmark swing on the page is GPQA, 96 to 71.2.
GPT-5.1-Codex-Max is also the more expensive model on tokens at $2.00 input / $8.00 output per 1M tokens, versus $0.05 input / $0.40 output per 1M tokens for GPT-5 nano. That is roughly 20.0x on output cost alone.
Pick GPT-5.1-Codex-Max if you want the stronger benchmark profile. GPT-5 nano only becomes the better choice if you want the cheaper token bill.
GPT-5.1-Codex-Max
81.5
GPT-5 nano
71.2
GPT-5.1-Codex-Max
96.6
GPT-5 nano
85.2
GPT-5.1-Codex-Max is ahead overall, 87 to 31. The biggest single separator in this matchup is GPQA, where the scores are 96 and 71.2.
GPT-5.1-Codex-Max has the edge for knowledge tasks in this comparison, averaging 81.5 versus 71.2. Inside this category, GPQA is the benchmark that creates the most daylight between them.
GPT-5.1-Codex-Max has the edge for math in this comparison, averaging 96.6 versus 85.2. Inside this category, AIME 2025 is the benchmark that creates the most daylight between them.
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