Claude Opus 4.1 vs GPT-5.1-Codex
Compare Claude Opus 4.1 by Anthropic against GPT-5.1-Codex by OpenAI, in 6 community votes, claude opus 4.1 wins 100% of head-to-head duels, context windows of 200K vs 400K, tested across 52 shared challenges.
Reasoning: Claude Opus 4.1 wins 100% of votes
Our Verdict
Claude Opus 4.1Winner
GPT-5.1-CodexRunner-up
Pick Claude Opus 4.1. In 6 blind votes, Claude Opus 4.1 wins 100% of the time. That's not luck.
Claude Opus 4.1 particularly excels in Reasoning. GPT-5.1-Codex is 7.5x cheaper per token — worth considering if cost matters.
Clear winner
API pricing
Cost per 1M tokens
Claude Opus 4.1
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
47%
Claude Opus 4.1 uses 38.4x more emoji
Claude Opus 4.1
GPT-5.1-Codex
61%Vocabulary70%
87wSentence Length17w
0.54Hedging0.39
5.1Bold3.4
6.7Lists3.5
0.38Emoji0.00
1.68Headings0.50
0.13Transitions0.38
Based on 17 + 14 text responses
Research
What we learned reading every model
FAQ
