GPT-OSS 120B vs Llama 3.1 405B

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

Quick Verdict

Llama 3.1 405B wins overall with a score of 58 vs 42 (16 point difference).Llama 3.1 405B wins 4 out of 4 categories.

Knowledge

Llama 3.1 405B

GPT-OSS 120B

48.8

Llama 3.1 405B

68.5

51
MMLU
70
50
GPQA
70
48
SuperGPQA
68
46
OpenBookQA
66

Coding

Llama 3.1 405B

GPT-OSS 120B

43

Llama 3.1 405B

62

43
HumanEval
62

Mathematics

Llama 3.1 405B

GPT-OSS 120B

50

Llama 3.1 405B

69

51
AIME 2023
70
53
AIME 2024
72
52
AIME 2025
71
47
HMMT Feb 2023
66
49
HMMT Feb 2024
68
48
HMMT Feb 2025
67
50
BRUMO 2025
69

Reasoning

Llama 3.1 405B

GPT-OSS 120B

48

Llama 3.1 405B

67

49
SimpleQA
68
47
MuSR
66

Frequently Asked Questions

Which is better, GPT-OSS 120B or Llama 3.1 405B?

Llama 3.1 405B scores higher overall with 58 vs 42, a difference of 16 points across all benchmarks.

Which is better for knowledge tasks, GPT-OSS 120B or Llama 3.1 405B?

Llama 3.1 405B leads in knowledge tasks with an average score of 68.5 vs 48.8.

Which is better for coding, GPT-OSS 120B or Llama 3.1 405B?

Llama 3.1 405B leads in coding with an average score of 62 vs 43.

Which is better for math, GPT-OSS 120B or Llama 3.1 405B?

Llama 3.1 405B leads in math with an average score of 69 vs 50.

Which is better for reasoning, GPT-OSS 120B or Llama 3.1 405B?

Llama 3.1 405B leads in reasoning with an average score of 67 vs 48.