Grok-4-Fast
by xAIChat
Fast Grok model for responsive chat, reasoning, and tool-assisted work
- Context
- 2M tokens
- Max output
- 2,000,000 tokens
- Released
- 2025-09-20
- Weights
- Closed
xai/grok-4-fast · also seen as x-ai/grok-4-fast
Specifications
Full facts as recorded, incl. what is unknown.
- Released
- 2025-09-20
- Weights
- Closed
- Input
- Text, Image, Audio, Video
- Output
- Text
- Context window
- 2,000,000 max across endpoints
- Max output
- 2,000,000
- Providers
- 1 + 1 gateway, not counted as providers
- Epoch Capabilities Index
- 144.2 ± 2.2 against price
- Direct price range
- $5.00 in · $25 out per 1M tokens · from its one provider
More details
- Last updated
- 2025-09-20
- Knowledge cutoff
- Developer country
- United States of America
Capabilities
Across all endpoints: supported if any endpoint supports it.
- Tool calling
- Parallel toolsunknown
- Structured output
- Reasoning
- Image input
- PDF input
- Audio input
- Audio outputunknown
- Video input
- Prompt cachingunknown
- Web searchunknown
- Computer useunknown
- System messagesunknown
- Assistant prefillunknown
- Temperature
- Streamingunknown
- Attachments
Endpoints
One row per provider and variant; gateways are listed separately.
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Price history
No change since 19 Oct 2026. The cheapest direct price has been $5.00 in / $25 out per 1M tokens at OCI Generative AI on every data refresh since then.
Tracked from 19 Oct 2026. Headline-eligible direct prices only, so a price the sanity check flags never draws a spike. Series as JSON
Cost calculator
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Heads up: prices are indicative list rates scraped from provider pricing pages; verify with the provider before relying on them. Report incorrect data for this model