benchlm.ai

GPT-5.3 Codex vs Grok 4.1 Fast

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 73 (12 point difference).GPT-5.3 Codex wins 4 out of 4 categories.

GPT-5.3 Codex

CreatorOpenAI
TypeProprietary
Context400K
Score85

Grok 4.1 Fast

CreatorxAI
TypeProprietary
Context2M
Score73

Knowledge

GPT-5.3 Codex

GPT-5.3 Codex

96

Grok 4.1 Fast

91

99
MMLU
94
97
GPQA
92
95
SuperGPQA
90
93
OpenBookQA
88

Coding

GPT-5.3 Codex

GPT-5.3 Codex

95

Grok 4.1 Fast

86

95
HumanEval
86

Mathematics

GPT-5.3 Codex

GPT-5.3 Codex

97.1

Grok 4.1 Fast

95

99
AIME 2023
96
99
AIME 2024
98
98
AIME 2025
97
95
HMMT Feb 2023
92
97
HMMT Feb 2024
94
96
HMMT Feb 2025
93
96
BRUMO 2025
95

Reasoning

GPT-5.3 Codex

GPT-5.3 Codex

94

Grok 4.1 Fast

89

95
SimpleQA
90
93
MuSR
88

Frequently Asked Questions

Which is better, GPT-5.3 Codex or Grok 4.1 Fast?

GPT-5.3 Codex scores higher overall with 85 vs 73, a difference of 12 points across all benchmarks.

Which is better for knowledge tasks, GPT-5.3 Codex or Grok 4.1 Fast?

GPT-5.3 Codex leads in knowledge tasks with an average score of 96 vs 91.

Which is better for coding, GPT-5.3 Codex or Grok 4.1 Fast?

GPT-5.3 Codex leads in coding with an average score of 95 vs 86.

Which is better for math, GPT-5.3 Codex or Grok 4.1 Fast?

GPT-5.3 Codex leads in math with an average score of 97.1 vs 95.

Which is better for reasoning, GPT-5.3 Codex or Grok 4.1 Fast?

GPT-5.3 Codex leads in reasoning with an average score of 94 vs 89.

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