xAI Documents Grok 4.20 with Reasoning and 1M Token Context

ArticlexAIResource

xAI's developer documentation details the specifications and pricing for Grok 4.20. The multimodal model features a 1-million-token context window, reasoning capabilities, and tool calling.

Key points

  1. Input modalities cover text and image, output is text.
  2. Context window reaches up to 1,000,000 tokens.
  3. Includes reasoning, function calling, and structured outputs.
  4. Pricing under 200k prompt tokens is $1.25 input, $0.20 cached input, and $2.50 output per million tokens.
  5. Pricing doubles across the entire request when prompts reach or exceed 200k tokens; Batch API gives a 20% discount.
  6. Available in us-east-1 and us-west-2 with rate limits of 37 RPS and 10 million TPM.

Why it matters

The model specifications define xAI's developer offering for large-context, agentic workflows with integrated reasoning.

Analysis

xAI highlights Grok 4.20 for prompt adherence, low hallucination rates, and speed. A key architectural and operational detail is the tiered pricing: crossing the 200,000 prompt token threshold applies the higher rate retroactively to all tokens in that request.

Mentioned links

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Summary generated by AI (Gemini 3.8 Flash, 27 September 2026). It may contain errors – the original source is authoritative.

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