benchlm.ai

GPT-5.3 Codex vs Kimi K2

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 23 (62 point difference).GPT-5.3 Codex wins 4 out of 4 categories.

GPT-5.3 Codex

CreatorOpenAI
TypeProprietary
Context400K
Score85

Kimi K2

CreatorMoonshot AI
TypeProprietary
Context128K
Score23

Knowledge

GPT-5.3 Codex

GPT-5.3 Codex

96

Kimi K2

29.8

99
MMLU
32
97
GPQA
31
95
SuperGPQA
29
93
OpenBookQA
27

Coding

GPT-5.3 Codex

GPT-5.3 Codex

95

Kimi K2

24

95
HumanEval
24

Mathematics

GPT-5.3 Codex

GPT-5.3 Codex

97.1

Kimi K2

31

99
AIME 2023
32
99
AIME 2024
34
98
AIME 2025
33
95
HMMT Feb 2023
28
97
HMMT Feb 2024
30
96
HMMT Feb 2025
29
96
BRUMO 2025
31

Reasoning

GPT-5.3 Codex

GPT-5.3 Codex

94

Kimi K2

29

95
SimpleQA
30
93
MuSR
28

Frequently Asked Questions

Which is better, GPT-5.3 Codex or Kimi K2?

GPT-5.3 Codex scores higher overall with 85 vs 23, a difference of 62 points across all benchmarks.

Which is better for knowledge tasks, GPT-5.3 Codex or Kimi K2?

GPT-5.3 Codex leads in knowledge tasks with an average score of 96 vs 29.8.

Which is better for coding, GPT-5.3 Codex or Kimi K2?

GPT-5.3 Codex leads in coding with an average score of 95 vs 24.

Which is better for math, GPT-5.3 Codex or Kimi K2?

GPT-5.3 Codex leads in math with an average score of 97.1 vs 31.

Which is better for reasoning, GPT-5.3 Codex or Kimi K2?

GPT-5.3 Codex leads in reasoning with an average score of 94 vs 29.

Related Comparisons

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