GPT-5.3 Chat vs GPT-5.6 Luna
Compare GPT-5.3 Chat and GPT-5.6 Luna, both from OpenAI, context windows of 128K vs 1.1M, tested across 53 shared challenges.
Our Verdict
GPT-5.3 Chat
GPT-5.6 Luna
No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.
Too close to call
API pricing
Cost per 1M tokens
GPT-5.3 Chat
Input
$1.75
Output
$14.00
GPT-5.6 Luna
Input
$1.00
1.8× cheaper
Output
$6.00
2.3× cheaper
GPT-5.6 Luna is cheaper on both — 1.8× input, 2.3× output
Writing DNA
Style Comparison
Similarity
64%
GPT-5.6 Luna uses 119.5x more headings
GPT-5.3 Chat
GPT-5.6 Luna
59%Vocabulary59%
26wSentence Length19w
0.84Hedging0.84
1.7Bold2.7
6.6Lists4.5
0.00Emoji0.00
0.00Headings1.20
0.25Transitions0.10
Based on 23 + 27 text responses
Research
What we learned reading every model
FAQ
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