GPT-OSS 120B vs GPT-OSS 20B

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

Quick Verdict

GPT-OSS 120B wins overall with a score of 42 vs 22 (20 point difference).GPT-OSS 120B wins 4 out of 4 categories.

Knowledge

GPT-OSS 120B

GPT-OSS 120B

48.8

GPT-OSS 20B

28.8

51
MMLU
31
50
GPQA
30
48
SuperGPQA
28
46
OpenBookQA
26

Coding

GPT-OSS 120B

GPT-OSS 120B

43

GPT-OSS 20B

23

43
HumanEval
23

Mathematics

GPT-OSS 120B

GPT-OSS 120B

50

GPT-OSS 20B

30

51
AIME 2023
31
53
AIME 2024
33
52
AIME 2025
32
47
HMMT Feb 2023
27
49
HMMT Feb 2024
29
48
HMMT Feb 2025
28
50
BRUMO 2025
30

Reasoning

GPT-OSS 120B

GPT-OSS 120B

48

GPT-OSS 20B

28

49
SimpleQA
29
47
MuSR
27

Frequently Asked Questions

Which is better, GPT-OSS 120B or GPT-OSS 20B?

GPT-OSS 120B scores higher overall with 42 vs 22, a difference of 20 points across all benchmarks.

Which is better for knowledge tasks, GPT-OSS 120B or GPT-OSS 20B?

GPT-OSS 120B leads in knowledge tasks with an average score of 48.8 vs 28.8.

Which is better for coding, GPT-OSS 120B or GPT-OSS 20B?

GPT-OSS 120B leads in coding with an average score of 43 vs 23.

Which is better for math, GPT-OSS 120B or GPT-OSS 20B?

GPT-OSS 120B leads in math with an average score of 50 vs 30.

Which is better for reasoning, GPT-OSS 120B or GPT-OSS 20B?

GPT-OSS 120B leads in reasoning with an average score of 48 vs 28.