Claude Opus 4.1 vs GPT-5.3-Codex
Compare Claude Opus 4.1 by Anthropic against GPT-5.3-Codex by OpenAI, context windows of 200K vs 400K, tested across 53 shared challenges.
Our Verdict
GPT-5.3-Codex
Claude Opus 4.1Runner-up
No community votes yet. On paper, GPT-5.3-Codex has the edge — newer, bigger context window.
GPT-5.3-Codex is 5.4x cheaper per token — worth considering if cost matters.
Too close to call
API pricing
Cost per 1M tokens
Claude Opus 4.1
Input
$15.00
Output
$75.00
GPT-5.3-Codex
Input
$1.75
8.6× cheaper
Output
$14.00
5.4× cheaper
GPT-5.3-Codex is cheaper on both — 8.6× input, 5.4× output
Writing DNA
Style Comparison
Similarity
61%
Claude Opus 4.1 uses 4.6x more transitions
Claude Opus 4.1
GPT-5.3-Codex
61%Vocabulary65%
87wSentence Length23w
0.54Hedging0.51
5.1Bold6.5
6.7Lists6.2
0.38Emoji0.16
1.68Headings1.90
0.13Transitions0.03
Based on 17 + 23 text responses
Research
What we learned reading every model
FAQ
