GPT-5.1 vs GPT-OSS 20B

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

Quick Verdict

GPT-5.1 wins overall with a score of 76 vs 22 (54 point difference).GPT-5.1 wins 4 out of 4 categories.

Knowledge

GPT-5.1

GPT-5.1

94

GPT-OSS 20B

28.8

97
MMLU
31
95
GPQA
30
93
SuperGPQA
28
91
OpenBookQA
26

Coding

GPT-5.1

GPT-5.1

89

GPT-OSS 20B

23

89
HumanEval
23

Mathematics

GPT-5.1

GPT-5.1

97.1

GPT-OSS 20B

30

99
AIME 2023
31
99
AIME 2024
33
98
AIME 2025
32
95
HMMT Feb 2023
27
97
HMMT Feb 2024
29
96
HMMT Feb 2025
28
96
BRUMO 2025
30

Reasoning

GPT-5.1

GPT-5.1

92

GPT-OSS 20B

28

93
SimpleQA
29
91
MuSR
27

Frequently Asked Questions

Which is better, GPT-5.1 or GPT-OSS 20B?

GPT-5.1 scores higher overall with 76 vs 22, a difference of 54 points across all benchmarks.

Which is better for knowledge tasks, GPT-5.1 or GPT-OSS 20B?

GPT-5.1 leads in knowledge tasks with an average score of 94 vs 28.8.

Which is better for coding, GPT-5.1 or GPT-OSS 20B?

GPT-5.1 leads in coding with an average score of 89 vs 23.

Which is better for math, GPT-5.1 or GPT-OSS 20B?

GPT-5.1 leads in math with an average score of 97.1 vs 30.

Which is better for reasoning, GPT-5.1 or GPT-OSS 20B?

GPT-5.1 leads in reasoning with an average score of 92 vs 28.