GPT-4.5 vs GPT-5.1
Compare GPT-4.5 and GPT-5.1, both from OpenAI, context windows of 128K vs 400K, tested across 24 shared challenges.
Our Verdict
GPT-5.1
GPT-4.5Runner-up
No community votes yet. On paper, GPT-5.1 has the edge — newer, bigger context window.
GPT-5.1 is 15x cheaper per token — worth considering if cost matters.
Too close to call
API pricing
Cost per 1M tokens
GPT-4.5
Input
$75.00
Output
$150.00
GPT-5.1
Input
$1.25
60× cheaper
Output
$10.00
15× cheaper
GPT-5.1 is cheaper on both — 60× input, 15× output
Writing DNA
Style Comparison
Similarity
56%
GPT-4.5 uses 19.6x more transitions
GPT-4.5
GPT-5.1
63%Vocabulary62%
16wSentence Length19w
0.57Hedging0.29
4.7Bold3.5
6.4Lists7.2
0.00Emoji0.00
1.30Headings0.61
0.54Transitions0.03
Based on 11 + 14 text responses
Research
What we learned reading every model
FAQ
Common questions
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