benchlm.ai

GPT-5.1-Codex-Max vs o3

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

Quick Verdict

GPT-5.1-Codex-Max wins overall with a score of 77 vs 67 (10 point difference).GPT-5.1-Codex-Max wins 4 out of 4 categories.

GPT-5.1-Codex-Max

CreatorOpenAI
TypeProprietary
Context400K
Score77

o3

CreatorOpenAI
TypeProprietary
Context200K
Score67

Knowledge

GPT-5.1-Codex-Max

GPT-5.1-Codex-Max

95

o3

85.3

98
MMLU
86
96
GPQA
87
94
SuperGPQA
85
92
OpenBookQA
83

Coding

GPT-5.1-Codex-Max

GPT-5.1-Codex-Max

94

o3

78

94
HumanEval
78

Mathematics

GPT-5.1-Codex-Max

GPT-5.1-Codex-Max

97.1

o3

87

99
AIME 2023
88
99
AIME 2024
90
98
AIME 2025
89
95
HMMT Feb 2023
84
97
HMMT Feb 2024
86
96
HMMT Feb 2025
85
96
BRUMO 2025
87

Reasoning

GPT-5.1-Codex-Max

GPT-5.1-Codex-Max

93

o3

83

94
SimpleQA
84
92
MuSR
82

Frequently Asked Questions

Which is better, GPT-5.1-Codex-Max or o3?

GPT-5.1-Codex-Max scores higher overall with 77 vs 67, a difference of 10 points across all benchmarks.

Which is better for knowledge tasks, GPT-5.1-Codex-Max or o3?

GPT-5.1-Codex-Max leads in knowledge tasks with an average score of 95 vs 85.3.

Which is better for coding, GPT-5.1-Codex-Max or o3?

GPT-5.1-Codex-Max leads in coding with an average score of 94 vs 78.

Which is better for math, GPT-5.1-Codex-Max or o3?

GPT-5.1-Codex-Max leads in math with an average score of 97.1 vs 87.

Which is better for reasoning, GPT-5.1-Codex-Max or o3?

GPT-5.1-Codex-Max leads in reasoning with an average score of 93 vs 83.

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