Elon Musk’s xAI has announced the release of Grok 4 Fast, a more efficient version of its reasoning model that is now available to all Grok users, including those on the free tier. The new model is accessible across web, iOS, and Android platforms and is designed to provide faster results with significantly lower resource usage and cost.
What is Grok 4 Fast?
According to xAI, Grok 4 Fast delivers performance comparable to the original Grok 4 model but uses 40% fewer “thinking tokens” on average. The company claims this efficiency gain results in a:
“98% reduction in price to achieve the same performance on frontier benchmarks as Grok 4.”
The model uses a unified architecture that allows it to switch between two different operational modes. For simple requests, it uses a “non-reasoning model” to generate quick answers. For more complex tasks, it engages a more powerful “reasoning model.” This dual-system approach is similar to the architecture reportedly used in OpenAI’s GPT-5, which also alternates between a fast, efficient model and a deeper reasoning model depending on the query’s complexity.
How to use Grok 4 Fast
For users who already have access to Grok, the new Grok 4 Fast model is now the default option.
To ensure you are using it, follow these steps:
- Open the Grok interface on the web or through the iOS or Android app.
- Look for the model selector, located at the top of the chat window.
- Confirm that “Grok 4 Fast” is selected. If you need to perform a more complex task, you can switch to the more powerful “Grok 4” model from this same menu.
No additional steps are needed to enable the new model. The free tier will automatically default to Grok 4 Fast for all queries.
Performance and competitive context
In side-by-side evaluations on the platform LMArena, Grok 4 Fast ranked first in search-related tasks and eighth in text-related tasks. The release comes as xAI faces ongoing challenges, including a recent controversy over antisemitic content generated by its chatbot.
The launch of a more efficient and accessible model is a clear move to attract more users and compete in a crowded market that includes Google’s Gemini, Anthropic’s Claude, and OpenAI’s ChatGPT.
