xAI: Grok 4 Fast
Analysis Summary
Grok 4 Fast is a high-throughput model from xAI with an intelligence index of 27.4 and an agentic index of 42.4. LiveCodeBench at 83.2% is among the stronger coding scores in the mid-tier, and GPQA at 84.7% reflects capable reasoning. Vision support and file input add multimodal capability, and the 2 million token context window is a standout feature for large-scale document or codebase analysis.
For businesses, Grok 4 Fast suits coding assistance, agentic tool-use pipelines, long-document analysis, and multimodal workflows. The combination of vision, tool use, function calling, and a 2M context window gives it broad capability breadth that few models at this price point match. Instruction following (aa_ifbench 0.505) is adequate rather than leading.
At $0.20 input and $0.50 output, it is one of the most cost-effective options for its capability level. Teams needing a fast, versatile model for mixed workloads, particularly those involving long documents or vision tasks, will find Grok 4 Fast a strong value proposition.
Assessed July 10, 2026
Editorial notes
Grok 4 Fast from xAI pairs strong coding and agentic scores with vision support, a 2M token context window, and very competitive pricing at $0.20 input per million tokens.
Rankings consider pricing, capabilities, benchmarks, and real-world applicability and are refreshed as new models launch. Feedback?
Performance Profile
How xAI: Grok 4 Fast compares
XAI: Grok 4 Fast ranks #100 of 392 AI models we track for overall intelligence, #118 of 296 for agentic tasks. Its 2M-token context window is larger than 100% of the models we list. At $0.20 per million input tokens it is cheaper than 55% of comparable models.
About xAI: Grok 4 Fast
Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Read more about the model..
Capabilities
Performance Indices
Source: Artificial Analysis
Benchmark Scores
Intelligence
Technical
Content
Benchmark data from Artificial Analysis and Hugging Face
How does xAI: Grok 4 Fast stack up?
Compare side-by-side with other professional models.
Model Information
| OpenRouter ID |
x-ai/grok-4-fast
|
| Provider | x-ai |
| Release Date | September 19, 2025 |
| Context Length | 2,000,000 tokens |
| Max Completion | 30,000 tokens |
| Status | Active |
Pricing
| Token Type | Cost per 1M tokens | Cost per 1K tokens |
|---|---|---|
| Input | $0.20 | $0.000200 |
| Output | $0.50 | $0.000500 |
Leaderboard Categories
External Resources
Frequently asked questions about xAI: Grok 4 Fast
How much does xAI: Grok 4 Fast cost?
xAI: Grok 4 Fast costs $0.20 per million input tokens and $0.50 per million output tokens.
What is the context window of xAI: Grok 4 Fast?
xAI: Grok 4 Fast has a context window of 2,000,000 tokens (2M).
What can xAI: Grok 4 Fast do?
xAI: Grok 4 Fast supports image/vision input, tool use, and function calling.
Who created xAI: Grok 4 Fast?
xAI: Grok 4 Fast is developed by xAI and was released on September 19, 2025.
