Z.ai: GLM 5.1 vs GPT-5
Compare Z.ai: GLM 5.1 by Z-ai against GPT-5 by OpenAI, context windows of 203K vs 400K, tested across 50 shared challenges.
Our Verdict
GPT-5
Z.ai: GLM 5.1Runner-up
No community votes yet. On paper, GPT-5 has the edge — bigger model tier, bigger context window, major provider backing.
Too close to call
API pricing
Cost per 1M tokens
Z.ai: GLM 5.1
Input
$1.40
Output
$4.40
2.3× cheaper
GPT-5
Input
$1.25
1.1× cheaper
Output
$10.00
GPT-5 wins input (1.1× cheaper)·Z.ai: GLM 5.1 wins output (2.3× cheaper)
Writing DNA
Style Comparison
Similarity
48%
Z.ai: GLM 5.1 uses 19.3x more bold
Z.ai: GLM 5.1
GPT-5
54%Vocabulary65%
18wSentence Length13w
0.31Hedging0.20
3.6Bold0.2
2.6Lists4.6
0.00Emoji0.00
0.43Headings0.16
0.11Transitions0.03
Based on 27 + 16 text responses
Research
What we learned reading every model
FAQ
