GPT-5.1 vs GPT-OSS 120B

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

Quick Verdict

GPT-5.1 wins overall with a score of 76 vs 42 (34 point difference).GPT-5.1 wins 4 out of 4 categories.

Knowledge

GPT-5.1

GPT-5.1

94

GPT-OSS 120B

48.8

97
MMLU
51
95
GPQA
50
93
SuperGPQA
48
91
OpenBookQA
46

Coding

GPT-5.1

GPT-5.1

89

GPT-OSS 120B

43

89
HumanEval
43

Mathematics

GPT-5.1

GPT-5.1

97.1

GPT-OSS 120B

50

99
AIME 2023
51
99
AIME 2024
53
98
AIME 2025
52
95
HMMT Feb 2023
47
97
HMMT Feb 2024
49
96
HMMT Feb 2025
48
96
BRUMO 2025
50

Reasoning

GPT-5.1

GPT-5.1

92

GPT-OSS 120B

48

93
SimpleQA
49
91
MuSR
47

Frequently Asked Questions

Which is better, GPT-5.1 or GPT-OSS 120B?

GPT-5.1 scores higher overall with 76 vs 42, a difference of 34 points across all benchmarks.

Which is better for knowledge tasks, GPT-5.1 or GPT-OSS 120B?

GPT-5.1 leads in knowledge tasks with an average score of 94 vs 48.8.

Which is better for coding, GPT-5.1 or GPT-OSS 120B?

GPT-5.1 leads in coding with an average score of 89 vs 43.

Which is better for math, GPT-5.1 or GPT-OSS 120B?

GPT-5.1 leads in math with an average score of 97.1 vs 50.

Which is better for reasoning, GPT-5.1 or GPT-OSS 120B?

GPT-5.1 leads in reasoning with an average score of 92 vs 48.