GPT-4 vs GPT-5.1-Codex
Compare GPT-4 and GPT-5.1-Codex, both from OpenAI, context windows of 8K vs 400K, tested across 26 shared challenges.
Our Verdict
GPT-5.1-Codex
GPT-4Runner-up
No community votes yet. On paper, GPT-5.1-Codex has the edge — newer, bigger context window.
GPT-5.1-Codex is 6.0x cheaper per token — worth considering if cost matters.
Too close to call
API pricing
Cost per 1M tokens
GPT-4
Input
$30.00
Output
$60.00
GPT-5.1-Codex
Input
$1.25
24× cheaper
Output
$10.00
6.0× cheaper
GPT-5.1-Codex is cheaper on both — 24× input, 6.0× output
Writing DNA
Style Comparison
Similarity
62%
GPT-5.1-Codex uses 50.1x more headings
GPT-4
GPT-5.1-Codex
59%Vocabulary70%
18wSentence Length17w
1.10Hedging0.39
0.8Bold3.4
2.5Lists3.5
0.00Emoji0.00
0.00Headings0.50
0.45Transitions0.38
Based on 15 + 14 text responses
Research
What we learned reading every model
FAQ
Common questions
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