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Grok 4.1 Fast

by xAI· Released 2026-01
Official Docs ↗

Grok 4.1 Fast offers a 2M token context window at $0.20/$0.50 per 1M tokens — the cheapest massive-context option on the market. It is ideal for long-document analysis, massive codebases, and high-throughput workloads that need huge context.

Input Price
$0.20/1M
per 1M tokens
Output Price
$0.50/1M
per 1M tokens
Context Window
2M tokens
max tokens
ELO Score
1305
LMSYS Arena

Pricing Breakdown

VolumeInput CostOutput CostCombined (50/50)
1,000 tokens$0.0002$0.0005$0.0003
10,000 tokens$0.0020$0.0050$0.0035
100,000 tokens$0.0200$0.0500$0.0350
1,000,000 tokens$0.2000$0.5000$0.3500

Strengths

  • 2M token context at $0.20/$0.50 per 1M — unbeatable for long context
  • Very fast inference
  • Real-time X data access
  • Reasoning and non-reasoning variants

Weaknesses

  • Weaker on hardest tasks vs. Grok 4.20
  • Ecosystem still smaller than OpenAI

Best For

long contextlow costfast responsesummarizationresearch

Compare Grok 4.1 Fast With

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Grok 4.1 Fast vs o3
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Grok 4.1 Fast vs Claude Sonnet 4.6
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Grok 4.1 Fast vs Gemini 2.5 Pro
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Frequently Asked Questions

How much does Grok 4.1 Fast cost?

Grok 4.1 Fast costs $0.20/1M per 1M input tokens and $0.50/1M per 1M output tokens.

What is Grok 4.1 Fast's context window?

Grok 4.1 Fast has a context window of 2M tokens, which means it can process up to 2,000,000 tokens in a single request.

Is Grok 4.1 Fast open source?

No, Grok 4.1 Fast is a proprietary model by xAI and is not open source.

What is Grok 4.1 Fast best used for?

Grok 4.1 Fast is best suited for: long-context, low-cost, fast-response, summarization, research. 2M token context at $0.20/$0.50 per 1M — unbeatable for long context.

What is Grok 4.1 Fast's ELO score?

Grok 4.1 Fast has an ELO score of 1305 on the LMSYS Chatbot Arena leaderboard, placing it among top-tier models.