xAI last week unveiled Grok 4 Fast, introducing a cost-efficient reasoning model that achieves comparable performance to Grok 4 while reducing token costs by 98%. The model features cost-efficiency with web and X search capabilities, a 2 million token context window, and unified architecture blending reasoning and non-reasoning modes.
Built on xAI's learnings from Grok 4, the new model delivers frontier-level performance across enterprise and consumer domains with exceptional token efficiency. Using large-scale reinforcement learning to maximise intelligence density, Grok 4 Fast achieves comparable performance to Grok 4 on benchmarks while using 40% fewer thinking tokens on average.
According to independent verification from Artificial Analysis, Grok 4 Fast exhibits a state-of-the-art price-to-intelligence ratio compared to other publicly available models on the Artificial Analysis Intelligence Index. The model scored 85.7% on GPQA Diamond, 92.0% on AIME 2025, and 93.3% on HMMT 2025 benchmarks.
The model was trained end-to-end with tool-use reinforcement learning, excelling at deciding when to invoke tools like code execution or web browsing. It demonstrates frontier agentic search capabilities, seamlessly browsing the web and X to augment queries with real-time data while ingesting media including images and videos.
Grok 4 Fast introduces unified architecture where reasoning and non-reasoning modes operate through the same model weights, steered via system prompts. This unification reduces end-to-end latency and token costs, making the model ideal for real-time enterprise applications requiring both quick responses for simple queries and extended reasoning for complex analysis.
The 98% cost reduction combined with maintained performance creates significant opportunities for enterprise AI deployment at scale. Organisations can now access frontier-level reasoning capabilities while dramatically reducing operational expenses. The model's availability across multiple platforms including xAI API, OpenRouter, and Vercel AI Gateway provides flexible integration options for enterprise developers seeking cost-effective AI solutions.