Side-by-side benchmark comparison across knowledge, coding, math, and reasoning.
GPT-4.1 is clearly ahead on the aggregate, 43 to 34. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-4.1's sharpest advantage is in knowledge, where it averages 78.3 against 28.2. The single biggest benchmark swing on the page is MMLU, 90.2 to 31. GPT-OSS 20B does hit back in mathematics, so the answer changes if that is the part of the workload you care about most.
GPT-4.1 gives you the larger context window at 1M, compared with 128K for GPT-OSS 20B.
Pick GPT-4.1 if you want the stronger benchmark profile. GPT-OSS 20B only becomes the better choice if mathematics is the priority.
GPT-4.1
78.3
GPT-OSS 20B
28.2
GPT-4.1
54.6
GPT-OSS 20B
16
GPT-4.1
26.4
GPT-OSS 20B
33.6
GPT-4.1
87.4
GPT-OSS 20B
67
GPT-4.1 is ahead overall, 43 to 34. The biggest single separator in this matchup is MMLU, where the scores are 90.2 and 31.
GPT-4.1 has the edge for knowledge tasks in this comparison, averaging 78.3 versus 28.2. Inside this category, MMLU is the benchmark that creates the most daylight between them.
GPT-4.1 has the edge for coding in this comparison, averaging 54.6 versus 16. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.
GPT-OSS 20B has the edge for math in this comparison, averaging 33.6 versus 26.4. Inside this category, AIME 2024 is the benchmark that creates the most daylight between them.
GPT-4.1 has the edge for instruction following in this comparison, averaging 87.4 versus 67. Inside this category, IFEval is the benchmark that creates the most daylight between them.
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