OpenAI: GPT-5.6 Luna Pro vs Grok Code Fast 1
Compare OpenAI: GPT-5.6 Luna Pro by OpenAI against Grok Code Fast 1 by xAI, context windows of 1.1M vs 256K, tested across 54 shared challenges.
Our Verdict
OpenAI: GPT-5.6 Luna Pro
Grok Code Fast 1Runner-up
No community votes yet. On paper, OpenAI: GPT-5.6 Luna Pro has the edge — newer, bigger context window.
Grok Code Fast 1 is 4.0x 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
Grok Code Fast 1
Input
$0.20
5.0× cheaper
Output
$1.50
4.0× cheaper
Grok Code Fast 1 is cheaper on both — 5.0× input, 4.0× output
Writing DNA
Style Comparison
Similarity
74%
OpenAI: GPT-5.6 Luna Pro uses 9.0x more emoji
OpenAI: GPT-5.6 Luna Pro
Grok Code Fast 1
58%Vocabulary60%
18wSentence Length17w
0.81Hedging0.97
2.9Bold2.8
5.1Lists2.5
0.54Emoji0.06
1.10Headings0.89
0.09Transitions0.11
Based on 27 + 23 text responses
Research
What we learned reading every model
FAQ
