Grok 4 Fast — Retired model

Retired modelThis model has reached end of life and is no longer available through BazaarLink. Historical specifications and independent benchmarks remain below. Retired on May 18, 2026.

Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Read more about the model on xAI's [news post](http://x.ai/news/grok-4-fast). Reasoning can be enabled/disabled using the `reasoning` `enabled` parameter in the API. Learn more in our docs

Provider	xAI
Released	September 2025
Model ID	`x-ai/grok-4-fast`

Technical specifications

Context window

2M tokens

Reasoning

—

Input

TextImageFile

Output

Text

Independent benchmarks

Scores below come from Artificial Analysis, an independent third party. BazaarLink does not participate in the testing.

Intelligence 11

Coding

Math 41

MMLU 73

GPQA 61

This modelCategory leader

Overall intelligence

#326out of 638 models

Aggregated across academic benchmarks

Intelligence

Mid-tier

This model

Category leader

Median

Math

—

This model

Category leader

Median

MMLU Pro

73%

—

This model

73%

Category leader

90%

Median

75%

GPQA

61%

—

This model

61%

Category leader

94%

Median

69%

LiveCodeBench

40%

—

This model

40%

Category leader

42%

Median

42%

HLE

—

This model

Category leader

53%

Median

SciCode

33%

—

This model

33%

Category leader

60%

Median

34%

IFBench

38%

—

This model

38%

Category leader

83%

Median

44%

τ²-Bench Telecom

64%

—

This model

64%

Category leader

99%

Median

46%

AA-LCR

20%

—

This model

20%

Category leader

76%

Median

40%

Terminal-Bench Hard

12%

—

This model

12%

Category leader

66%

Median

14%

Top 5 — CodingCoding Index leaderboard

1Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback)?/claude-fable-5-182$10 / $50

2Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback)?/claude-fable-5-1-xhigh81$10 / $50

3Claude Fable 5.1 (Adaptive Reasoning, High Effort, Default Fallback)?/claude-fable-5-1-high79$10 / $50

4GPT-5.6 Sol (xhigh)openai/gpt-5-6-sol-xhigh78$4 / $20

5Claude Opus 5 (Adaptive Reasoning, Max Effort)anthropic/claude-opus-578$5 / $25

AASource: Artificial Analysis · Independent third-party evaluation; not influenced by BazaarLinkView full evaluation on AA →

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Frequently Asked Questions

Can I still use the retired Grok 4 Fast model?

No. Grok 4 Fast has been retired and is retained here only as a historical reference. See the active alternatives linked on this page.

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Grok 4 Fast — Retired model

Technical specifications

Independent benchmarks

Top 5 — CodingCoding Index leaderboard

Frequently Asked Questions

Relay integrity checks

Related models and links