benchlm.ai

GPT-5.1 vs GPT-5.3 Codex

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

Quick Verdict

GPT-5.3 Codex wins overall with a score of 85 vs 76 (9 point difference).GPT-5.3 Codex wins 3 out of 4 categories.

GPT-5.1

CreatorOpenAI
TypeProprietary
Context400K
Score76

GPT-5.3 Codex

CreatorOpenAI
TypeProprietary
Context400K
Score85

Knowledge

GPT-5.3 Codex

GPT-5.1

94

GPT-5.3 Codex

96

97
MMLU
99
95
GPQA
97
93
SuperGPQA
95
91
OpenBookQA
93

Coding

GPT-5.3 Codex

GPT-5.1

89

GPT-5.3 Codex

95

89
HumanEval
95

Mathematics

Tie

GPT-5.1

97.1

GPT-5.3 Codex

97.1

99
AIME 2023
99
99
AIME 2024
99
98
AIME 2025
98
95
HMMT Feb 2023
95
97
HMMT Feb 2024
97
96
HMMT Feb 2025
96
96
BRUMO 2025
96

Reasoning

GPT-5.3 Codex

GPT-5.1

92

GPT-5.3 Codex

94

93
SimpleQA
95
91
MuSR
93

Frequently Asked Questions

Which is better, GPT-5.1 or GPT-5.3 Codex?

GPT-5.3 Codex scores higher overall with 85 vs 76, a difference of 9 points across all benchmarks.

Which is better for knowledge tasks, GPT-5.1 or GPT-5.3 Codex?

GPT-5.3 Codex leads in knowledge tasks with an average score of 96 vs 94.

Which is better for coding, GPT-5.1 or GPT-5.3 Codex?

GPT-5.3 Codex leads in coding with an average score of 95 vs 89.

Which is better for math, GPT-5.1 or GPT-5.3 Codex?

GPT-5.1 and GPT-5.3 Codex are tied for math with average scores of 97.1.

Which is better for reasoning, GPT-5.1 or GPT-5.3 Codex?

GPT-5.3 Codex leads in reasoning with an average score of 94 vs 92.

Related Comparisons

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