Z.ai: GLM 5.1
The Z.ai: GLM 5.1 model is designed for processing text inputs within a context length of up to 204,800 tokens and supports up to 128,000 completion tokens per interaction. It can handle tasks that involve text input modalities and comes equipped with reasoning capabilities. For users seeking an AI solution with robust reasoning capabilities at a moderate price point, the Z.ai: GLM 5.1 model is worth considering. With a blended benchmark score of 65.8 across two independent benchmarks, it demonstrates competitive performance. However, its pricing structure, including $0.966 per million input tokens and $3.036 per million output tokens, may be out of range for those with very tight budgets or who require extremely low-cost processing.
Benchmark results
Independent, published benchmarks. Blended score 65.8 across 2 benchmarks, last refreshed 2026-09-10. How scoring works →
| Benchmark | Measures | Score |
|---|---|---|
| AI Index | broad capability composite | 43.6 |
| 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
- 128,000 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 $0.97/M input and $3.04/M output rates. Run your own numbers →
| Job | Tokens | Cost |
|---|---|---|
| Summarize a 50-page report | 30k in / 1.5k out | $0.03 |
| Classify 1,000 customer emails | 500k in / 50k out | $0.63 |
| A month of a busy support chatbot | 5M in / 2M out | $10.90 |
Price & spec history
Tracked daily by PicksByModel since 2026-07-17.
| Date | Input /M | Output /M | Context |
|---|---|---|---|
| 2026-09-01 | $0.97 | $3.04 | 204,800 |
| 2026-08-25 | $1.26 | $3.96 | 204,800 |
| 2026-08-15 | $0.97 | $3.04 | 204,800 |
| 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 5.2
Z.ai: GLM 5.3 (batch)
Z.ai: GLM 5.2 (batch)
Z.ai: GLM 5 Turbo
Z.ai: GLM 5
Z.ai: GLM 4.7
Quick answers
- How much does Z.ai: GLM 5.1 cost?
- $0.97 per million input tokens and $3.04 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.