A high-speed, highly intelligent, and concise model from xAI, offering a strong balance of performance and cost-efficiency for real-time applications.
Grok 4.1 Fast emerges from xAI as a formidable contender in the AI landscape, specifically engineered for applications where speed and responsiveness are paramount. Positioned as the high-velocity variant of their Grok series, this model is tailored for real-time interactions, such as sophisticated chatbots, live content generation, and rapid data summarization. It distinguishes itself not just by its speed but by maintaining a high level of intelligence, challenging the common trade-off between quick responses and cognitive depth. This unique combination makes it a compelling choice for developers looking to build fluid, engaging, and smart user experiences without the latency penalties often associated with top-tier models.
The performance metrics for Grok 4.1 Fast are impressive. It achieves a median output speed of 122.5 tokens per second, placing it comfortably above the class average of 93 tokens/s. This throughput is complemented by a low latency (time to first token) of just 0.52 seconds, ensuring that applications feel snappy and interactive. What truly sets it apart, however, is that this speed does not come at a significant cost to its intellectual capabilities. Scoring 38 on the Artificial Analysis Intelligence Index, it substantially outperforms the average score of 28 for comparable models. This indicates a strong ability to handle nuanced queries, generate coherent text, and perform complex instructions accurately, all while delivering results at a rapid pace.
From a cost perspective, Grok 4.1 Fast is positioned competitively. Its input price of $0.20 per 1 million tokens is slightly below the market average, while its output price of $0.50 per 1 million tokens also offers good value. A key, often overlooked, factor in its cost-effectiveness is its conciseness. During benchmark testing, the model generated only 6.5 million tokens to complete tasks where the average model produced 11 million. Because output tokens are 2.5 times more expensive than input tokens, this natural brevity can lead to significant cost savings in output-heavy applications. The total cost to run the comprehensive Intelligence Index benchmark on this model was a modest $15.38, underscoring its overall economic efficiency.
Beyond its core performance and pricing, Grok 4.1 Fast is equipped with cutting-edge technical specifications. It boasts a massive 2 million token context window, enabling it to process and analyze vast amounts of information—equivalent to entire novels or extensive code repositories—in a single pass. This capability unlocks powerful use cases in legal document review, research synthesis, and maintaining long-term memory in conversational AI. Furthermore, the model supports multimodal inputs, accepting both text and images. This allows for more versatile applications, such as analyzing visual data or answering questions about a supplied image, with the final output delivered as text. Currently available exclusively via the xAI API, it represents a powerful, self-contained ecosystem for developers.
38 (17 / 77)
122.5 tokens/s
$0.20 / 1M tokens
$0.50 / 1M tokens
6.5M tokens
0.52 seconds
| Spec | Details |
|---|---|
| Owner | xAI |
| License | Proprietary |
| Context Window | 2,000,000 tokens |
| Input Modalities | Text, Image |
| Output Modalities | Text |
| API Provider | xAI |
| Input Price | $0.20 / 1M tokens |
| Output Price | $0.50 / 1M tokens |
| Blended Price (3:1) | $0.28 / 1M tokens |
| Median Latency (TTFT) | 0.52 seconds |
| Median Output Speed | 122.5 tokens/second |
Grok 4.1 Fast is currently available exclusively through its creator, xAI. This simplifies the choice of provider to a single option, but it also means that all users are tied to one source for API access, performance, and pricing. Your decision is not which provider to use, but whether the sole provider's offering fits your needs.
| Priority | Pick | Why | Tradeoff to accept |
|---|---|---|---|
| Top Performance | xAI | As the sole provider and creator, xAI offers direct, optimized access to the model's full capabilities, including its speed and massive context window. | No alternative options for performance tuning, regional availability, or failover. |
| Lowest Price | xAI | The only available price point is the one set by xAI, making it the de facto cheapest (and most expensive) option. | There is no ability to shop around for better rates, volume discounts, or different pricing models that might be offered in a competitive market. |
| Simplicity | xAI | With only one API to integrate, the development process is straightforward and documentation is centralized. | Lack of provider-specific features, value-add services, or specialized support that might be offered by a competitive marketplace. |
Performance and pricing data are based on benchmarks conducted by Artificial Analysis on the xAI API. As the model ecosystem evolves, other providers may become available, which could alter these recommendations.
Theoretical prices per million tokens can be abstract. To understand the real-world financial impact of using Grok 4.1 Fast, let's model its cost across a few common application scenarios. These estimates use the benchmarked prices of $0.20/1M input tokens and $0.50/1M output tokens.
| Scenario | Input | Output | What it represents | Estimated cost |
|---|---|---|---|---|
| Customer Support Chatbot | 1,500 tokens (history) | 200 tokens (response) | A single turn in an ongoing support conversation. | $0.0004 |
| Email Summarization | 2,000 tokens (email thread) | 150 tokens (summary) | Processing one long email for a user's inbox. | $0.000475 |
| Code Generation | 500 tokens (description) | 300 tokens (code) | A developer requesting a simple utility function. | $0.00025 |
| RAG Document Query | 8,000 tokens (query + context) | 400 tokens (answer) | Answering a question using a retrieval-augmented generation system. | $0.0018 |
| Large Document Analysis | 100,000 tokens (report) | 1,000 tokens (takeaways) | A one-off analysis of a significant document. | $0.025 |
| Content Ideation | 100 tokens (topic) | 800 tokens (ideas list) | Generating a list of blog post ideas from a single topic. | $0.00042 |
The model's extremely low per-transaction cost makes it highly suitable for high-volume, interactive applications like chatbots. Costs become more noticeable only when processing very large inputs, but its natural conciseness helps keep output expenses in check across all workloads.
Grok 4.1 Fast's pricing is competitive, but costs can accumulate quickly in a production environment. A strategic approach to implementation is key to maximizing its value while managing your budget. Here are several strategies to consider to ensure cost-efficiency.
The model's greatest cost-saving feature is its natural brevity. Since output tokens cost 2.5x more than input tokens, every token you avoid generating is a direct saving. You can encourage this behavior further with careful prompting.
The 2 million token context window is a powerful tool, but filling it unnecessarily is a fast way to increase costs. For most tasks, a much smaller, targeted context is more efficient.
Many applications receive identical or very similar user queries over time. Caching responses can eliminate redundant API calls and dramatically reduce costs.
You cannot control what you cannot measure. Proactive monitoring is essential to prevent budget overruns, especially when scaling an application.
Grok 4.1 Fast is a large language model from xAI. It is a variant of the Grok 4.1 family, specifically optimized for high-speed output and low latency, making it ideal for real-time, interactive applications while still maintaining a high level of intelligence.
The 'Non-reasoning' tag suggests the model is tuned for fast, direct responses rather than complex, multi-step logical deduction. It excels at tasks like summarization, question-answering, and creative writing where a quick and coherent response is valued. It may be less suited for intricate problem-solving that requires deep, sequential thought, which is likely the domain of a corresponding 'Reasoning' model.
The 2 million token context window allows the model to process and 'remember' a vast amount of information within a single request. This is equivalent to roughly 1.5 million words. It enables powerful use cases like analyzing an entire book, a large codebase, or a lengthy financial report in one go, allowing for deep synthesis and cross-referencing of information.
Yes, it is multimodal on the input side. It can accept both text and images as part of a prompt. However, its output is limited to text only. This allows you to ask questions about an image or have it analyze visual information, but it will respond with a textual description or answer.
The ideal user is a developer or business building applications that require a combination of high intelligence, low latency, and high throughput. This includes creators of advanced chatbots, real-time content generation tools, live data analysis systems, and any service where a fast, smart response is critical to the user experience.
Currently, Grok 4.1 Fast is available exclusively through the API provided by its creator, xAI. There are no other third-party providers offering access to this model at this time.