GPT-OSS 120B vs o3

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

Quick Verdict

o3 wins overall with a score of 67 vs 42 (25 point difference).o3 wins 4 out of 4 categories.

Knowledge

o3

GPT-OSS 120B

48.8

o3

85.3

51
MMLU
86
50
GPQA
87
48
SuperGPQA
85
46
OpenBookQA
83

Coding

o3

GPT-OSS 120B

43

o3

78

43
HumanEval
78

Mathematics

o3

GPT-OSS 120B

50

o3

87

51
AIME 2023
88
53
AIME 2024
90
52
AIME 2025
89
47
HMMT Feb 2023
84
49
HMMT Feb 2024
86
48
HMMT Feb 2025
85
50
BRUMO 2025
87

Reasoning

o3

GPT-OSS 120B

48

o3

83

49
SimpleQA
84
47
MuSR
82

Frequently Asked Questions

Which is better, GPT-OSS 120B or o3?

o3 scores higher overall with 67 vs 42, a difference of 25 points across all benchmarks.

Which is better for knowledge tasks, GPT-OSS 120B or o3?

o3 leads in knowledge tasks with an average score of 85.3 vs 48.8.

Which is better for coding, GPT-OSS 120B or o3?

o3 leads in coding with an average score of 78 vs 43.

Which is better for math, GPT-OSS 120B or o3?

o3 leads in math with an average score of 87 vs 50.

Which is better for reasoning, GPT-OSS 120B or o3?

o3 leads in reasoning with an average score of 83 vs 48.