Z.ai: GLM 5.1
Z.ai: GLM 5.1 is designed for handling text inputs with a context length of up to 204800 tokens and supports reasoning and tools, making it suitable for complex tasks that require both comprehension and action. While it lacks structured output capabilities, its comprehensive input modalities and tool support make it a robust choice for developers looking to integrate advanced AI functionalities. Given its blended benchmark score of 74.7 across four independent benchmarks, Z.ai: GLM 5.1 is competitive in terms of performance but may be more expensive than other options, with pricing at $1.4 per million input tokens and $4.4 per million output tokens. This model is ideal for those willing to invest in a powerful tool for complex text-based tasks, especially when reasoning and tool integration are critical.
Benchmark results
Independent, published benchmarks. Blended score 74.7 across 4 benchmarks, last refreshed 2026-08-13. How scoring works →
| Benchmark | Measures | Score |
|---|---|---|
| AI Index | broad capability composite | 67.6 |
| AI Index Coding | software engineering tasks | 92.0 |
| AI Index Agentic | multi-step tool-using tasks | 50.4 |
| EQ-Bench | emotional understanding in dialogue | 75.2 |
- Model ID
- z-ai/glm-5.1
- Vendor
- z-ai
- Released
- April 2026
- Tokenizer
- Other
- Input Modalities
- text
- Output Modalities
- text
- Max Output
- 131,072 tokens
- Tool Calling
- ✓ supported
- Structured Output
- ✓ supported
- Reasoning Mode
- ✓ supported
- Vision
- text only
- Audio
- no
- Moderated
- no
What it costs in practice
Computed from the current $1.40/M input and $4.40/M output rates. Run your own numbers →
| Job | Tokens | Cost |
|---|---|---|
| Summarize a 50-page report | 30k in / 1.5k out | $0.05 |
| Classify 1,000 customer emails | 500k in / 50k out | $0.92 |
| A month of a busy support chatbot | 5M in / 2M out | $15.80 |
Price & spec history
Tracked daily by PicksByModel since 2026-07-17.
| Date | Input /M | Output /M | Context |
|---|---|---|---|
| 2026-08-10 | $1.40 | $4.40 | 204,800 |
| 2026-08-06 | $0.95 | $2.99 | 204,800 |
| 2026-07-22 | $0.97 | $3.04 | 204,800 |
| 2026-07-17 | $0.97 | $3.04 | 202,752 |
Similar models
Z.ai: GLM 5 Turbo
Z.ai: GLM 5.2
Z.ai: GLM 5
Z.ai: GLM 5.2 (batch)
Z.ai: GLM 4.6
Z.ai: GLM 4.7
Quick answers
- How much does Z.ai: GLM 5.1 cost?
- $1.40 per million input tokens and $4.40 per million output tokens.
- What is Z.ai: GLM 5.1's context window?
- 204,800 tokens, roughly 307 pages of text in a single request.
- Does Z.ai: GLM 5.1 support tool calling?
- It supports tool calling, structured output, a reasoning mode.
- Can Z.ai: GLM 5.1 process images?
- No, it is text-only on the input side.