Benchable
Text input
Image input
Text output
Free Option
Author's Description
Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Read more about the model on xAI's [news post](http://x.ai/news/grok-4-fast). Reasoning can be enabled using the `reasoning` `enabled` parameter in the API. [Learn more in our docs](https://openrouter.ai/docs/use-cases/reasoning-tokens#controlling-reasoning-tokens) Prompts and completions may be used by xAI or OpenRouter to improve future models.
Key Specifications
Context
2M
Released
Sep 18, 2025
Supported Parameters
This model supports the following parameters:
Tools
Include Reasoning
Temperature
Top Logprobs
Tool Choice
Seed
Response Format
Max Tokens
Structured Outputs
Reasoning
Top P
Logprobs
Features
This model supports the following features:
Structured Outputs
Reasoning
Tools
Response Format
Model Pricing
Current Pricing
| Feature | Price (per 1M tokens) |
|---|---|
| Prompt | $0.2 |
| Completion | $0.5 |
| Input Cache Read | $0.05 |
Price History
Available Endpoints
| Provider | Endpoint Name | Context Length | Pricing (Input) | Pricing (Output) |
|---|---|---|---|---|
|
xAI
|
xAI | x-ai/grok-4-fast | 2M | $0.2 / 1M tokens | $0.5 / 1M tokens |
No benchmark execution results are available for this model yet.
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|
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|
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|---|---|---|---|---|---|---|---|
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★★★★★ | ★★★ | $$$$$ |
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