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Grok 4 Fast

Cost-efficient Grok 4 family with 2M context and reasoning/non-reasoning modes.

Creator
xAI
Lifecycle
Active
Context
2.0M
Max output
—
Released
Jan 10, 2026
Status
up
Input
$0.20 / 1M tokens
Output
$0.50 / 1M tokens
Cached read
— / 1M tokens
Cached write
— / 1M tokens
Batch discount
—%
Source
Grok 4 Fast pricing
Verified
Apr 2, 2026 (High)

Capabilities

Modalities
textimage→text
Capabilities
reasoningwebSearchimageInputbatchSupportpromptCachingfunctionCallingstructuredOutputs
Strengths
Huge context window, Cheap Grok tier
Tradeoffs
Still evolving quickly
Official Links
Intro
https://docs.x.ai/developers/models
Docs
https://docs.x.ai/developers/models
Pricing
https://docs.x.ai/developers/models
Release note
https://docs.x.ai/docs/release-notes

Benchmark Coverage

BenchmarkVersionScoreDateSourceNotes

Release History

ReleaseAliasLifecycleRelease DateDeprecationShutdownSummary
Grok 4 Fastgrok-4-fastActiveJan 10, 2026——Current published model family snapshot.

Host Coverage

HostTypeContextPricing NoteDifferences
xAI APIfirst-party2.0MReference access to Grok 4 families.Structured outputs; Image input
Migration Guidance

Fast-tier alternative to Grok 4.20 beta for budget-sensitive workloads.

Replacement models: grok-4-20-beta

Change Events
DateTypeTitleDescriptionSource
Jan 10, 2026family_addedGrok 4 Fast publishedInitial public model family launch.Grok 4 Fast release notes

Other models from xAI

Grok 2, Grok 4.20 Beta, Grok Code Fast 1