o1 vs GPT-OSS 120B

Side-by-side benchmark comparison across knowledge, coding, math, and reasoning.

o1 finishes one point ahead overall, 51 to 50. That is enough to call, but not enough to treat as a blowout. This matchup comes down to a few meaningful edges rather than one model dominating the board.

o1's sharpest advantage is in knowledge, where it averages 83.8 against 43.8. The single biggest benchmark swing on the page is MMLU, 91.8 to 51.

o1 is the reasoning model in the pair, while GPT-OSS 120B is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. o1 gives you the larger context window at 200K, compared with 128K for GPT-OSS 120B.

Quick Verdict

Pick o1 if you want the stronger benchmark profile. GPT-OSS 120B only becomes the better choice if you would rather avoid the extra latency and token burn of a reasoning model.

Knowledge

o1

o1

83.8

GPT-OSS 120B

43.8

91.8
MMLU
51
75.7
GPQA
50
-
SuperGPQA
48
-
OpenBookQA
46
-
MMLU-Pro
63
-
HLE
5

Coding

o1

o1

41

GPT-OSS 120B

32.3

41
SWE-bench Verified
29
-
HumanEval
43
-
LiveCodeBench
25

Mathematics

o1

o1

74.3

GPT-OSS 120B

52.6

74.3
AIME 2024
53
-
AIME 2023
51
-
AIME 2025
52
-
HMMT Feb 2023
47
-
HMMT Feb 2024
49
-
HMMT Feb 2025
48
-
BRUMO 2025
50
-
MATH-500
71

Reasoning

GPT-OSS 120B
-
SimpleQA
49
-
MuSR
47
-
BBH
73

Instruction Following

o1

o1

92.2

GPT-OSS 120B

79

92.2
IFEval
79

Multilingual

GPT-OSS 120B
-
MGSM
72

Frequently Asked Questions

Which is better, o1 or GPT-OSS 120B?

o1 is ahead overall, 51 to 50. The biggest single separator in this matchup is MMLU, where the scores are 91.8 and 51.

Which is better for knowledge tasks, o1 or GPT-OSS 120B?

o1 has the edge for knowledge tasks in this comparison, averaging 83.8 versus 43.8. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, o1 or GPT-OSS 120B?

o1 has the edge for coding in this comparison, averaging 41 versus 32.3. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.

Which is better for math, o1 or GPT-OSS 120B?

o1 has the edge for math in this comparison, averaging 74.3 versus 52.6. Inside this category, AIME 2024 is the benchmark that creates the most daylight between them.

Which is better for instruction following, o1 or GPT-OSS 120B?

o1 has the edge for instruction following in this comparison, averaging 92.2 versus 79. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Last updated: March 9, 2026

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