Z.ai: GLM 5.1 vs GPT-5.4
Compare Z.ai: GLM 5.1 by Z-ai against GPT-5.4 by OpenAI, context windows of 203K vs 1.1M, tested across 52 shared challenges.
Our Verdict
GPT-5.4
Z.ai: GLM 5.1Runner-up
No community votes yet. On paper, GPT-5.4 has the edge — bigger model tier, bigger context window, major provider backing.
Z.ai: GLM 5.1 is 3.4x 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
1.8× cheaper
Output
$4.40
3.4× cheaper
GPT-5.4
Input
$2.50
Output
$15.00
Z.ai: GLM 5.1 is cheaper on both — 1.8× input, 3.4× output
Writing DNA
Style Comparison
Similarity
30%
Z.ai: GLM 5.1 uses 5.7x more transitions
Z.ai: GLM 5.1
GPT-5.4
54%Vocabulary54%
18wSentence Length28w
0.31Hedging0.69
3.6Bold4.1
2.6Lists8.1
0.00Emoji0.00
0.43Headings1.84
0.11Transitions0.02
Based on 27 + 22 text responses
Research
What we learned reading every model
FAQ
