Claude Opus 4 vs GPT-5.1-Codex
Compare Claude Opus 4 by Anthropic against GPT-5.1-Codex by OpenAI, context windows of 200K vs 400K, tested across 52 shared challenges.
Our Verdict
GPT-5.1-Codex
Claude Opus 4Runner-up
No community votes yet. On paper, GPT-5.1-Codex has the edge — newer, bigger context window.
GPT-5.1-Codex is 7.5x cheaper per token — worth considering if cost matters.
Too close to call
API pricing
Cost per 1M tokens
Claude Opus 4
Input
$15.00
Output
$75.00
GPT-5.1-Codex
Input
$1.25
12× cheaper
Output
$10.00
7.5× cheaper
GPT-5.1-Codex is cheaper on both — 12× input, 7.5× output
Writing DNA
Style Comparison
Similarity
48%
Claude Opus 4 uses 11.2x more emoji
Claude Opus 4
GPT-5.1-Codex
64%Vocabulary70%
62wSentence Length17w
0.52Hedging0.39
4.4Bold3.4
9.1Lists3.5
0.11Emoji0.00
1.87Headings0.50
0.27Transitions0.38
Based on 16 + 14 text responses
Research
What we learned reading every model
FAQ
