What is the context window of Z.ai: GLM 5.1?

Z.ai: GLM 5.1 supports a context window of 204K tokens.

Is Z.ai: GLM 5.1 free to use?

Z.ai: GLM 5.1 is a paid model. It costs $1.40 per million input tokens and $4.40 per million output tokens.

How is LLM API pricing calculated?

LLM pricing has two components: input tokens (everything you send) and output tokens (what the model generates). Total cost = (prompt tokens × input rate + output tokens × output rate) / 1,000,000 × number of requests.

Z.ai: GLM 5.1 API Pricing — $1.40 Input / $4.40 Output per 1M Tokens

Q: How much does Z.ai: GLM 5.1 cost?

Z.ai: GLM 5.1 costs $1.40 per million input tokens and $4.40 per million output tokens via OpenRouter. Pricing was last updated Oct 29, 2026.

Z.ai: GLM 5.1 by Z Ai — $1.40 input / $4.40 output per 1M tokens via OpenRouter. Context: 204K tokens. Pricing last updated Oct 29, 2026.

Input / 1M tokens

$1.40

Output / 1M tokens

$4.40

Provider

Z Ai

Context window

204K tokens

Via

OpenRouter

Cost at common usage volumes

Usage	Daily	Monthly
Chatbot (100/day)	$0.620	$18.60
Small app (1K/day)	$3.60	$108.00
Mid-scale (10K/day)	$50.00	$1500.00
Large scale (100K/day)	$1140.00	$34200.00

Model ID: z-ai/glm-5.1
Data source: OpenRouter public API — updated Oct 29, 2026.

← Full cost calculator Compare models →

Ad · 336x280

About Z.ai: GLM 5.1

Z.ai: GLM 5.1 is an LLM developed by Z Ai. Input costs $1.40 per million tokens and output costs $4.40 per million tokens via OpenRouter. It supports a context window of 204K tokens.

Pricing Details

Via the OpenRouter API:

Input tokens: $1.40 per 1 million tokens
Output tokens: $4.40 per 1 million tokens

A token is roughly 0.75 words. For context: a typical user message of 100 words is approximately 133 tokens; a 500-word system prompt is about 650 tokens.

How Much Does Z.ai: GLM 5.1 Cost?

For a typical chatbot application (1,000 requests/day, 1,000 prompt tokens and 500 output tokens per request):

Daily cost: $3.6000
Monthly cost: $108.000

Accessing Z.ai: GLM 5.1 via OpenRouter

OpenRouter provides a unified API for 200+ LLMs including Z.ai: GLM 5.1. You can use it with any OpenAI-compatible SDK by setting the base URL to https://openrouter.ai/api/v1 and using your OpenRouter API key. The model ID is z-ai/glm-5.1.

Compare Z.ai: GLM 5.1 with Other Models

Use the AI Model Cost Comparison tool to compare Z.ai: GLM 5.1 against GPT-4o, Claude 3.5 Sonnet, Gemini 1.5 Pro, or any other model side by side. Or use the LLM API Cost Calculator to browse all 456+ models sorted by cost for your specific usage.

Frequently Asked Questions

Yes. Z.ai: GLM 5.1 is available on OpenRouter with the model ID z-ai/glm-5.1. OpenRouter provides a unified API compatible with OpenAI's SDK format.