Z.ai: GLM 5.1 vs GPT-4
Compare Z.ai: GLM 5.1 by Z-ai against GPT-4 by OpenAI, context windows of 203K vs 8K, tested across 20 shared challenges. Updated April 2026.
Which is better, Z.ai: GLM 5.1 or GPT-4?
Z.ai: GLM 5.1 and GPT-4 are both competitive models. Z.ai: GLM 5.1 costs $1.4/M input tokens vs $30/M for GPT-4. Context windows: 203K vs 8K tokens. Compare their real outputs side by side below.
Key Differences Between Z.ai: GLM 5.1 and GPT-4
Z.ai: GLM 5.1 is made by z-ai while GPT-4 is from openai. Z.ai: GLM 5.1 has a 203K token context window compared to GPT-4's 8K. On pricing, Z.ai: GLM 5.1 costs $1.4/M input tokens vs $30/M for GPT-4.
Our Verdict
Z.ai: GLM 5.1
GPT-4
No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.
Z.ai: GLM 5.1 is 14x cheaper per token — worth considering if cost matters.
Too close to call
Writing DNA
Style Comparison
Similarity
94%
Z.ai: GLM 5.1 uses 43.5x more headings
Z.ai: GLM 5.1
GPT-4
54%Vocabulary59%
18wSentence Length18w
0.31Hedging1.10
3.6Bold0.8
2.6Lists2.5
0.00Emoji0.00
0.43Headings0.00
0.11Transitions0.45
Based on 27 + 15 text responses
vsAsk them anything yourself
Some models write identically. You are paying for the brand.
178 models fingerprinted across 32 writing dimensions. Free research.
Model Similarity Index
185x
price gap between models that write identically
178
models
12
clone pairs
32
dimensions
Devstral M / S
95.7%
Qwen3 Coder / Flash
95.6%
GPT-5.4 / Mini
93.3%
279 AI models invented the same fake scientist.
We read every word. 250 models. 2.14 million words. This is what we found.
Free preview13 of 58 slides
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