Grok 4 Fast Reasoning

xAI

xAI's previous-generation thinking model with 2M context and cost-efficient agentic performance. Combined rapid execution with reasoning capabilities.

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Capabilities

Thinking

Tool Use

Image Input

Image Generation

Example Use Cases

Agentic workflow with reasoning

Huge context with thinking

Rapid intelligent agents

Technical Specifications

Context Window

2,000,000 tokens

Max Output

256,000 tokens

Pricing

Token Costs (per 1M tokens)

Cache Miss Input

$0.20

Non-Reasoning Output

$0.50

Cache Read Input

$0.05

Tool Costs (per 1K calls)

Web Search

$5

Code Execution

$5

Image Generation

$70

Legacy

Made legacy on

Reason

Outdated model

Recommended Replacement

Grok 4.20 Reasoning