benchlm.ai

GPT-5.1-Codex-Max vs Z-1

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 43 (34 point difference).GPT-5.1-Codex-Max wins 4 out of 4 categories.

GPT-5.1-Codex-Max

CreatorOpenAI
TypeProprietary
Context400K
Score77

Z-1

CreatorZ
TypeProprietary
Context128K
Score43

Knowledge

GPT-5.1-Codex-Max

GPT-5.1-Codex-Max

95

Z-1

49.8

98
MMLU
52
96
GPQA
51
94
SuperGPQA
49
92
OpenBookQA
47

Coding

GPT-5.1-Codex-Max

GPT-5.1-Codex-Max

94

Z-1

44

94
HumanEval
44

Mathematics

GPT-5.1-Codex-Max

GPT-5.1-Codex-Max

97.1

Z-1

51

99
AIME 2023
52
99
AIME 2024
54
98
AIME 2025
53
95
HMMT Feb 2023
48
97
HMMT Feb 2024
50
96
HMMT Feb 2025
49
96
BRUMO 2025
51

Reasoning

GPT-5.1-Codex-Max

GPT-5.1-Codex-Max

93

Z-1

49

94
SimpleQA
50
92
MuSR
48

Frequently Asked Questions

Which is better, GPT-5.1-Codex-Max or Z-1?

GPT-5.1-Codex-Max scores higher overall with 77 vs 43, a difference of 34 points across all benchmarks.

Which is better for knowledge tasks, GPT-5.1-Codex-Max or Z-1?

GPT-5.1-Codex-Max leads in knowledge tasks with an average score of 95 vs 49.8.

Which is better for coding, GPT-5.1-Codex-Max or Z-1?

GPT-5.1-Codex-Max leads in coding with an average score of 94 vs 44.

Which is better for math, GPT-5.1-Codex-Max or Z-1?

GPT-5.1-Codex-Max leads in math with an average score of 97.1 vs 51.

Which is better for reasoning, GPT-5.1-Codex-Max or Z-1?

GPT-5.1-Codex-Max leads in reasoning with an average score of 93 vs 49.

Related Comparisons

GPT-5.1-Codex-Max vs GPT-5.4GPT-5.1-Codex-Max vs Gemini 3.1 ProGPT-5.1-Codex-Max vs Claude Opus 4.6GPT-5.1-Codex-Max vs GPT-5.3 CodexGPT-5.1-Codex-Max vs Grok 4.1GPT-5.1-Codex-Max vs GPT-5.2