Grok 4.1 Fast
xAI's efficiency model. Long-context specialist with 2M window.
Scores by test
Methodology →What you need to know
Grok 4.1 Fast is defined by its massive 2M token context window and high reliability in structured output and persona consistency. It achieves perfect internal scores in faithfulness and strategic analysis, making it a strong candidate for complex reasoning tasks that require strict adherence to a specific voice or format.
At a blended cost of $0.425/MTok, the model is priced competitively for its capability set. While it ranks #84 out of 130 models overall, its specialized strengths in long-context processing and multilingual support provide higher utility for specific architectural needs than its general rank suggests.
The model has a critical failure in safety calibration, scoring 1/5, which indicates a lack of restrictive filtering or guardrails. It also shows relative weakness in handling tabular data and basic classification compared to its other high-performing domains.
Use this model if you need a low-cost engine for massive document analysis, strict JSON/structured outputs, or highly consistent persona-driven agents. Skip this model if your application requires strict safety filtering or heavy manipulation of tabular data.
Strengths — Top 3
Relative weaknesses — Bottom 3
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