GPT-5 mini vs GPT-OSS 120B

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

Quick Verdict

GPT-5 mini wins overall with a score of 68 vs 42 (26 point difference).GPT-5 mini wins 4 out of 4 categories.

Knowledge

GPT-5 mini

GPT-5 mini

85

GPT-OSS 120B

48.8

88
MMLU
51
86
GPQA
50
84
SuperGPQA
48
82
OpenBookQA
46

Coding

GPT-5 mini

GPT-5 mini

80

GPT-OSS 120B

43

80
HumanEval
43

Mathematics

GPT-5 mini

GPT-5 mini

89

GPT-OSS 120B

50

90
AIME 2023
51
92
AIME 2024
53
91
AIME 2025
52
86
HMMT Feb 2023
47
88
HMMT Feb 2024
49
87
HMMT Feb 2025
48
89
BRUMO 2025
50

Reasoning

GPT-5 mini

GPT-5 mini

83

GPT-OSS 120B

48

84
SimpleQA
49
82
MuSR
47

Frequently Asked Questions

Which is better, GPT-5 mini or GPT-OSS 120B?

GPT-5 mini scores higher overall with 68 vs 42, a difference of 26 points across all benchmarks.

Which is better for knowledge tasks, GPT-5 mini or GPT-OSS 120B?

GPT-5 mini leads in knowledge tasks with an average score of 85 vs 48.8.

Which is better for coding, GPT-5 mini or GPT-OSS 120B?

GPT-5 mini leads in coding with an average score of 80 vs 43.

Which is better for math, GPT-5 mini or GPT-OSS 120B?

GPT-5 mini leads in math with an average score of 89 vs 50.

Which is better for reasoning, GPT-5 mini or GPT-OSS 120B?

GPT-5 mini leads in reasoning with an average score of 83 vs 48.