GPT-5.5 vs Z.ai: GLM 5.1
Side-by-side comparison. Updated 2026-06-09.
Verdict
GPT-5.5 wins on higher overall score (9.4 vs 9.1, +0.3).
Both models score equally. Pick based on which strengths align with your workload.
At a Glance
| Attribute | GPT-5.5 | Z.ai: GLM 5.1 |
|---|---|---|
| Provider | OpenAI | Z Ai |
| Tags | general | Intelligent Coding Agentic |
| Context | 128,000 tokens | 202,752 tokens |
| Input price | $12.50/1M | $0.98/1M |
| Output price | $3.08/1M | $3.08/1M |
| Input modalities | Text | Text |
| Output modalities | Text | Text |
GPT-5.5 Strengths
- Strong general knowledge
- Deep reasoning chain-of-thought
- Reliable structured output
- Broad tool-use capability
- Excellent multilingual support
Z.ai: GLM 5.1 Strengths
- Top-tier coding and long-horizon task completion
- Strong agentic reasoning for multi-step workflows
- Configurable reasoning depth for cost/quality tradeoffs
- Excellent instruction following on complex tasks