Grok 4.1 Fast Reasoning

Grok 4.1 Fast is xAI's best tool-calling model with a 2M context window. It reasons and completes agentic tasks accurately and rapidly, excelling at complex real-world use cases such as customer support and finance. To optimize for maximal intelligence use this variant. Otherwise, use the non-reasoning version.

Model overview

Model ID: xai/grok-4.1-fast-reasoning
Provider: xai
Type: language
Context window: 2,000,000 tokens
Max output tokens: 30,000

Tags: reasoning, tool-use, implicit-caching

Model pricing

Metric	Value
`Input tokens (/1M)`	`$0.20`
`Output tokens (/1M)`	`$0.50`
`Image generation`	`n/a`
`Cached input read (/1M)`	`$0.05`
`Cached input write (/1M)`	`n/a`
`Pricing source`	`gateway`

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