GPT-5.3 Codex vs Qwen3.5 397B (Reasoning)

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 70 (15 point difference).GPT-5.3 Codex wins 4 out of 4 categories.

Knowledge

GPT-5.3 Codex

GPT-5.3 Codex

96

Qwen3.5 397B (Reasoning)

88

99
MMLU
91
97
GPQA
89
95
SuperGPQA
87
93
OpenBookQA
85

Coding

GPT-5.3 Codex

GPT-5.3 Codex

95

Qwen3.5 397B (Reasoning)

83

95
HumanEval
83

Mathematics

GPT-5.3 Codex

GPT-5.3 Codex

97.1

Qwen3.5 397B (Reasoning)

92

99
AIME 2023
93
99
AIME 2024
95
98
AIME 2025
94
95
HMMT Feb 2023
89
97
HMMT Feb 2024
91
96
HMMT Feb 2025
90
96
BRUMO 2025
92

Reasoning

GPT-5.3 Codex

GPT-5.3 Codex

94

Qwen3.5 397B (Reasoning)

86

95
SimpleQA
87
93
MuSR
85

Frequently Asked Questions

Which is better, GPT-5.3 Codex or Qwen3.5 397B (Reasoning)?

GPT-5.3 Codex scores higher overall with 85 vs 70, a difference of 15 points across all benchmarks.

Which is better for knowledge tasks, GPT-5.3 Codex or Qwen3.5 397B (Reasoning)?

GPT-5.3 Codex leads in knowledge tasks with an average score of 96 vs 88.

Which is better for coding, GPT-5.3 Codex or Qwen3.5 397B (Reasoning)?

GPT-5.3 Codex leads in coding with an average score of 95 vs 83.

Which is better for math, GPT-5.3 Codex or Qwen3.5 397B (Reasoning)?

GPT-5.3 Codex leads in math with an average score of 97.1 vs 92.

Which is better for reasoning, GPT-5.3 Codex or Qwen3.5 397B (Reasoning)?

GPT-5.3 Codex leads in reasoning with an average score of 94 vs 86.