Side-by-side benchmark comparison across knowledge, coding, math, and reasoning.
o3-pro is clearly ahead on the aggregate, 77 to 31. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
o3-pro's sharpest advantage is in knowledge, where it averages 75 against 71.2. The single biggest benchmark swing on the page is GPQA, 89 to 71.2.
GPT-5 nano gives you the larger context window at 400K, compared with 200K for o3-pro.
Pick o3-pro if you want the stronger benchmark profile. GPT-5 nano only becomes the better choice if you need the larger 400K context window.
o3-pro
75
GPT-5 nano
71.2
o3-pro
89
GPT-5 nano
85.2
o3-pro is ahead overall, 77 to 31. The biggest single separator in this matchup is GPQA, where the scores are 89 and 71.2.
o3-pro has the edge for knowledge tasks in this comparison, averaging 75 versus 71.2. Inside this category, GPQA is the benchmark that creates the most daylight between them.
o3-pro has the edge for math in this comparison, averaging 89 versus 85.2. Inside this category, AIME 2025 is the benchmark that creates the most daylight between them.
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