GPT-5.2-Codex vs Z-1

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

Quick Verdict

GPT-5.2-Codex wins overall with a score of 82 vs 43 (39 point difference).GPT-5.2-Codex wins 4 out of 4 categories.

Knowledge

GPT-5.2-Codex

GPT-5.2-Codex

96

Z-1

49.8

99
MMLU
52
97
GPQA
51
95
SuperGPQA
49
93
OpenBookQA
47

Coding

GPT-5.2-Codex

GPT-5.2-Codex

95

Z-1

44

95
HumanEval
44

Mathematics

GPT-5.2-Codex

GPT-5.2-Codex

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-5.2-Codex

GPT-5.2-Codex

94

Z-1

49

95
SimpleQA
50
93
MuSR
48

Frequently Asked Questions

Which is better, GPT-5.2-Codex or Z-1?

GPT-5.2-Codex scores higher overall with 82 vs 43, a difference of 39 points across all benchmarks.

Which is better for knowledge tasks, GPT-5.2-Codex or Z-1?

GPT-5.2-Codex leads in knowledge tasks with an average score of 96 vs 49.8.

Which is better for coding, GPT-5.2-Codex or Z-1?

GPT-5.2-Codex leads in coding with an average score of 95 vs 44.

Which is better for math, GPT-5.2-Codex or Z-1?

GPT-5.2-Codex leads in math with an average score of 97.1 vs 51.

Which is better for reasoning, GPT-5.2-Codex or Z-1?

GPT-5.2-Codex leads in reasoning with an average score of 94 vs 49.