LLMAPI only

Grok 4 Fast

xAI

Updated May 21, 2026 · Benchmarks via Artificial Analysis, specs & pricing via OpenRouter · Methodology · Report an error

Specifications

Type: LLM
Access: API only
Released: September 19, 2025
License: Proprietary
Context window: 2,000,000 tokens
Output speed: 90 tok/s
Input: Text, Image
Output: Text
API pricing: $0.20 in · $0.50 out / 1M tokens

Capabilities

Function callingStructured outputWeb search

Benchmarks

Reasoning

85.7

Coding

80

Math

AIME 2025	92
HMMT 2025	93.3

Agents

44.9

General

Humanity’s Last Exam	20
SimpleQA	95
MMLU-Pro	85

Our take

Cheap, high-throughput Grok 4 with a 2M-token context and reasoning/non-reasoning variants, using far fewer thinking tokens than Grok 4.

Links

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