Claude Sonnet 4.5 vs GPT OSS 20B
Compare Claude Sonnet 4.5 by Anthropic against GPT OSS 20B by OpenAI, context windows of 200K vs 131K, tested across 43 shared challenges.
Our Verdict
Claude Sonnet 4.5
GPT OSS 20BRunner-up
No community votes yet. On paper, Claude Sonnet 4.5 has the edge — newer, bigger context window.
GPT OSS 20B is 150x cheaper per token — worth considering if cost matters.
Too close to call
API pricing
Cost per 1M tokens
Claude Sonnet 4.5
Input
$3.00
Output
$15.00
GPT OSS 20B
Input
$0.02
150× cheaper
Output
$0.10
150× cheaper
GPT OSS 20B is cheaper on both — 150× input, 150× output
Writing DNA
Style Comparison
Similarity
33%
Claude Sonnet 4.5 uses 5.5x more sentence length
Claude Sonnet 4.5
GPT OSS 20B
64%Vocabulary54%
94wSentence Length17w
0.48Hedging0.26
4.9Bold5.9
8.0Lists3.3
0.45Emoji0.10
1.91Headings0.75
0.07Transitions0.32
Based on 20 + 21 text responses
Research
What we learned reading every model
FAQ
