#13
Grok 4 Fast Reasoning
grok-4-fast-reasoning

Grok 4 Fast Reasoning is xAI's cost-efficient large-context model that targets near-frontier quality while dramatically reducing per-token costs. It delivers strong reasoning and instruction following on complex math, coding, and analytical tasks, landing between frontier models and earlier Grok generations in overall quality. Compared with Grok 4.1 Thinking it sacrifices a bit of peak text quality and creativity in exchange for much higher throughput, making it a great default for production assistants and agentic tools that need both depth and speed.

Performance Metrics

Helpfulness
Instruction Following
Comprehension
Empathy
Creative Writing
86.70
Helpfulness
89
Empathy
86.5
Instruction Following
91.5
Creative Writing
76
Comprehension
90.5
Speed
Avg 88 tok/s

Model Specifications

Release Date
September 19, 2025
Lab
xAI
Type
Proprietary
Context Size
2M
Max Output Tokens
8.2K
Cost per 1M tokens
$0.20 / $0.50
Model Inputs
Text, Images, Code, Web
Model Outputs
Text
Tool Calling
Enabled

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