Z.ai: GLM 5.1 vs OpenAI o3
Compare Z.ai: GLM 5.1 by Z-ai against OpenAI o3 by OpenAI, tested across 52 shared challenges.
Our Verdict
OpenAI o3
Z.ai: GLM 5.1Runner-up
No community votes yet. On paper, OpenAI o3 has the edge — bigger model tier, major provider backing.
Z.ai: GLM 5.1 is 9.1x cheaper per token — worth considering if cost matters.
Too close to call
API pricing
Cost per 1M tokens
Z.ai: GLM 5.1
Input
$1.40
7.1× cheaper
Output
$4.40
9.1× cheaper
OpenAI o3
Input
$10.00
Output
$40.00
Z.ai: GLM 5.1 is cheaper on both — 7.1× input, 9.1× output
Writing DNA
Style Comparison
Similarity
43%
Z.ai: GLM 5.1 uses 5.2x more bold
Z.ai: GLM 5.1
OpenAI o3
54%Vocabulary68%
18wSentence Length14w
0.31Hedging0.26
3.6Bold0.7
2.6Lists3.0
0.00Emoji0.00
0.43Headings0.38
0.11Transitions0.12
Based on 27 + 16 text responses
Research
What we learned reading every model
FAQ
