GPT-5 Pro vs GPT OSS 20B
Compare GPT-5 Pro and GPT OSS 20B, both from OpenAI, context windows of 400K vs 131K, tested across 42 shared challenges.
Our Verdict
GPT-5 Pro
GPT OSS 20BRunner-up
No community votes yet. On paper, GPT-5 Pro has the edge — bigger model tier, newer, bigger context window.
GPT OSS 20B is 1200x cheaper per token — worth considering if cost matters.
Slight edge
API pricing
Cost per 1M tokens
GPT-5 Pro
Input
$15.00
Output
$120.00
GPT OSS 20B
Input
$0.02
750× cheaper
Output
$0.10
1200× cheaper
GPT OSS 20B is cheaper on both — 750× input, 1200× output
Writing DNA
Style Comparison
Similarity
43%
GPT OSS 20B uses 591.9x more bold
GPT-5 Pro
GPT OSS 20B
65%Vocabulary54%
15wSentence Length17w
0.32Hedging0.26
0.0Bold5.9
2.9Lists3.3
0.00Emoji0.10
0.00Headings0.75
0.01Transitions0.32
Based on 11 + 21 text responses
Research
What we learned reading every model
FAQ
Common questions
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