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

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Outdated model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