OpenAI: GPT-5.6 Luna Pro vs GPT OSS 20B
Compare OpenAI: GPT-5.6 Luna Pro and GPT OSS 20B, both from OpenAI, context windows of 1.1M vs 131K, tested across 53 shared challenges.
Our Verdict
OpenAI: GPT-5.6 Luna Pro
GPT OSS 20B
No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.
GPT OSS 20B is 60x cheaper per token — worth considering if cost matters.
Too close to call
API pricing
Cost per 1M tokens
OpenAI: GPT-5.6 Luna Pro
Input
$1.00
Output
$6.00
GPT OSS 20B
Input
$0.02
50× cheaper
Output
$0.10
60× cheaper
GPT OSS 20B is cheaper on both — 50× input, 60× output
Writing DNA
Style Comparison
Similarity
43%
OpenAI: GPT-5.6 Luna Pro uses 5.3x more emoji
OpenAI: GPT-5.6 Luna Pro
GPT OSS 20B
58%Vocabulary54%
18wSentence Length17w
0.81Hedging0.26
2.9Bold5.9
5.1Lists3.3
0.54Emoji0.10
1.10Headings0.75
0.09Transitions0.32
Based on 27 + 21 text responses
Research
What we learned reading every model
FAQ
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