Claude Fable 5 vs OpenAI: GPT-5.6 Luna Pro
Compare Claude Fable 5 by Anthropic against OpenAI: GPT-5.6 Luna Pro by OpenAI, context windows of 1.0M vs 1.1M, tested across 54 shared challenges.
Our Verdict
Claude Fable 5
OpenAI: GPT-5.6 Luna ProRunner-up
No community votes yet. On paper, Claude Fable 5 has the edge — bigger model tier.
OpenAI: GPT-5.6 Luna Pro is 8.3x cheaper per token — worth considering if cost matters.
Too close to call
API pricing
Cost per 1M tokens
Claude Fable 5
Input
$10.00
Output
$50.00
OpenAI: GPT-5.6 Luna Pro
Input
$1.00
10× cheaper
Output
$6.00
8.3× cheaper
OpenAI: GPT-5.6 Luna Pro is cheaper on both — 10× input, 8.3× output
Writing DNA
Style Comparison
Similarity
60%
OpenAI: GPT-5.6 Luna Pro uses 1.8x more transitions
Claude Fable 5
OpenAI: GPT-5.6 Luna Pro
60%Vocabulary58%
22wSentence Length18w
0.49Hedging0.81
4.0Bold2.9
3.5Lists5.1
0.58Emoji0.54
1.09Headings1.10
0.05Transitions0.09
Based on 27 + 27 text responses
Research
What we learned reading every model
FAQ
