Side-by-side benchmark comparison across knowledge, coding, math, and reasoning.
GPT-5.3 Codex is clearly ahead on the aggregate, 92 to 33. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.3 Codex's sharpest advantage is in mathematics, where it averages 97.4 against 86. The single biggest benchmark swing on the page is GPQA, 97 to 79.
o1-pro is also the more expensive model on tokens at $150.00 input / $600.00 output per 1M tokens, versus $2.50 input / $10.00 output per 1M tokens for GPT-5.3 Codex. That is roughly 60.0x on output cost alone. GPT-5.3 Codex gives you the larger context window at 400K, compared with 200K for o1-pro.
Pick GPT-5.3 Codex if you want the stronger benchmark profile. o1-pro only becomes the better choice if its workflow or ecosystem matters more than the raw scoreboard.
GPT-5.3 Codex
86.3
o1-pro
79
GPT-5.3 Codex
97.4
o1-pro
86
GPT-5.3 Codex is ahead overall, 92 to 33. The biggest single separator in this matchup is GPQA, where the scores are 97 and 79.
GPT-5.3 Codex has the edge for knowledge tasks in this comparison, averaging 86.3 versus 79. Inside this category, GPQA is the benchmark that creates the most daylight between them.
GPT-5.3 Codex has the edge for math in this comparison, averaging 97.4 versus 86. Inside this category, AIME 2024 is the benchmark that creates the most daylight between them.
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