Z.ai: GLM 5.1 vs GPT-5.5
Compare Z.ai: GLM 5.1 by Z-ai against GPT-5.5 by OpenAI, context windows of 203K vs 1.1M, tested across 53 shared challenges. Updated May 2026.
Which is better, Z.ai: GLM 5.1 or GPT-5.5?
Z.ai: GLM 5.1 and GPT-5.5 are both competitive models. Z.ai: GLM 5.1 costs $1.4/M input tokens vs $5/M for GPT-5.5. Context windows: 203K vs 1050K tokens. Compare their real outputs side by side below.
Key Differences Between Z.ai: GLM 5.1 and GPT-5.5
Z.ai: GLM 5.1 is made by z-ai while GPT-5.5 is from openai. Z.ai: GLM 5.1 has a 203K token context window compared to GPT-5.5's 1050K. On pricing, Z.ai: GLM 5.1 costs $1.4/M input tokens vs $5/M for GPT-5.5.
Per 1M tokens
Z.ai: GLM 5.1 is cheaper on both — 3.6× input, 6.8× output
No community votes yet. On paper, GPT-5.5 has the edge — bigger model tier, bigger context window, major provider backing.
Z.ai: GLM 5.1 is 6.8x cheaper per token — worth considering if cost matters.
Style Comparison
GPT-5.5 uses 3.9x more headings
