Grok 4 Fast
xAI • LLM
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...
Specifications
Context Window
2.0M tokens
Input Price/1M
$0.20
Output Price/1M
$0.50
Parameters
—
Max Output
30K tokens
Benchmarks
Grok 4 Fast results on the main AI model evaluation benchmarks. Higher scores indicate better performance.
Agentic
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| Terminal-Bench Hard | 19.0 | 100.0 | — |
Coding
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| LiveCodeBench | 83.0 | 100.0 | Artificial Analysis official API |
| SciCode | 44.0 | 100.0 | — |
| AA Coding Index | 27.4 | 100.0 | Artificial Analysis official API |
Knowledge
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| MMLU-Pro | 85.0 | 100.0 | — |
Long Context
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| AA-LCR | 65.0 | 100.0 | — |
Math
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| AIME 2025 | 90.0 | 100.0 | Artificial Analysis official API |
| AA Math Index | 89.7 | 100.0 | Artificial Analysis official API |
overall
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| AA Intelligence Index | 35.1 | 100.0 | Artificial Analysis official API |
Reasoning
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| GPQA Diamond | 85.0 | 100.0 | Artificial Analysis official API |
| MMLU Pro | 73.0 | 100.0 | Artificial Analysis official API |
| IFBench | 51.0 | 100.0 | — |
| HLE | 17.0 | 100.0 | — |
Tool Use
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| Tau²-Bench | 66.0 | 100.0 | — |
Information
- Release date
- September 19, 2025
- Tool Calling
- ✅ Supported
- Vision
- ✅ Supported
- Audio
- ❌ Not supported
Full Analysis: Grok 4 Fast
What is Grok 4 Fast?
Grok 4 Fast is an AI model developed by xAI, classified as a large language model (LLM). It is a multimodal model, capable of processing text, images, and potentially other media types. As a proprietary model, it is available via xAI's cloud API. With a context window of 2.0M tokens, it is suitable for processing long documents such as contracts, books, and complete codebases.
Pricing & Costs in 2026
Grok 4 Fast is usage-based, priced at $0.2/1M input tokens and $0.5/1M output tokens. For context: 1 million tokens is approximately 750,000 words, or about 10 average-length books. At this aggressive price point, it is one of the most cost-effective options on the market, ideal for high-volume applications like chatbots, bulk document analysis, and automation.
Benchmarks & Performance
Grok 4 Fast was evaluated on 14 different benchmarks, covering categories like Agentic, Coding, Knowledge, Long Context, Math, overall, Reasoning, Tool Use. Results show exceptional performance across available evaluations.
It's important to note that benchmarks measure specific aspects and don't capture the full user experience. Factors like instruction adherence, behavior in long conversations, and real-world task quality vary significantly between models and aren't always reflected in standard scores.
Recommended Use Cases
Grok 4 Fast is suitable for a wide range of AI applications: long document analysis (contracts, legal proceedings, codebases), automation with tool calling (API integration, databases, external systems), image and visual document analysis (OCR, diagrams, screenshots), multimodal processing combining text and images, high-volume chatbots and automated support, complex reasoning, math problem solving, and logical analysis, text generation, summarization, translation, and general assistance.
Comparison with Alternatives
In the 2026 AI model ecosystem, Grok 4 Fast competes directly with similarly capable models. xAI competes in this segment against OpenAI, Anthropic, Google, and Meta. The choice between models depends on the specific use case, budget, latency requirements, and need for features like multimodality and tool calling.
For a detailed side-by-side comparison, use our comparison tool or check the overall model ranking.
Frequently Asked Questions
What is 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...
How much does Grok 4 Fast cost?
Grok 4 Fast costs $0.2/1M input tokens and $0.5/1M output tokens. For heavy usage (e.g., a chatbot handling 100k messages/month), costs can range from $10 to $1,000 depending on volume.
How does Grok 4 Fast compare with other models?
In available benchmarks, Grok 4 Fast scored: Terminal-Bench Hard: 19/100, LiveCodeBench: 83/100, SciCode: 44/100. See the full table above for a detailed comparison.
Is Grok 4 Fast open source?
No, Grok 4 Fast is a proprietary model from xAI. It is available via cloud API. For open source alternatives, check our open source model ranking.
What is Grok 4 Fast best for?
Grok 4 Fast excels at complex reasoning and problem solving. With its large context window, it handles long documents, codebases, and extended conversations. It supports tool calling for API integrations and automation.
Last updated: June 01, 2026 • View methodology →