xAI's Grok 4.1 Fast has landed, and the pricing is turning heads. At just 0.20permillioninputtokens∗∗and∗∗0.20 per million input tokens** and **0.50 per million output tokens, it's one of the most aggressively priced frontier-class models on the market — and it comes with a massive 2 million token context window that dwarfs most competitors.
Whether you're building RAG pipelines, processing entire codebases, or running agentic workflows with tool use, Grok 4.1 Fast offers a compelling price-to-performance ratio. But the headline numbers only tell part of the story. Automatic prompt caching, tool invocation fees, Batch API discounts, and third-party routing through services like Crazyrouter all affect your real-world costs.
In this guide, we'll break down every aspect of Grok 4.1 pricing so you can estimate your actual spend — and find ways to cut it further.
xAI currently offers two main API tiers. Here's how they compare side by side:
| Feature | Grok 4.1 Fast | Grok 4 |
|---|---|---|
| Input Price | $0.20 / MTok | $3.00 / MTok |
| Cached Input Price | $0.05 / MTok | $0.75 / MTok |
| Output Price | $0.50 / MTok | $15.00 / MTok |
| Context Window | 2,000,000 tokens | 256,000 tokens |
| Cache Discount | 75% off (0.25x) | 75% off (0.25x) |
| Best For | High-volume, cost-sensitive workloads | Complex reasoning, premium tasks |
The price gap is dramatic. Grok 4.1 Fast is 15x cheaper on input and 30x cheaper on output compared to Grok 4. For the vast majority of production workloads — chatbots, summarization, code generation, document processing — Grok 4.1 Fast is the obvious default choice.
Grok 4 still has its place for tasks that demand maximum reasoning depth, but at 3.00/3.00/15.00 per MTok, it's a premium tier you'd reserve for high-stakes use cases where quality justifies the cost.
Grok 4.1 Fast's 2 million token context window is a standout feature that changes how you architect applications. To put that in perspective:
A larger context window doesn't just mean convenience — it can actually reduce your total costs:
Fewer API calls. Instead of splitting a large document across multiple requests, you send it once. Fewer calls mean fewer output tokens wasted on repeated instructions and context-setting.
Better retrieval without RAG overhead. For many use cases, you can skip the complexity (and cost) of embedding pipelines, vector databases, and retrieval systems entirely. Just put the full document in context.
Reduced hallucination. When the model has access to the complete source material, it's less likely to fabricate information — saving you the cost of error correction and re-processing.
Agentic workflows benefit enormously. Multi-step agents that accumulate conversation history, tool outputs, and intermediate results can run much longer before hitting context limits.
At 0.20/MTokinput,fillingtheentire2Mcontextwindowcostsjust∗∗0.20/MTok input, filling the entire 2M context window costs just **0.40** — a remarkably low price for that much information density. Compare that to Grok 4, where 2M tokens of input (if it supported it) would cost $6.00.
One of the most impactful cost-saving features in the Grok API is automatic prompt caching. Here's how it works:
| Model | Standard Input | Cached Input | Savings |
|---|---|---|---|
| Grok 4.1 Fast | $0.20 / MTok | $0.05 / MTok | 75% |
| Grok 4 | $3.00 / MTok | $0.75 / MTok | 75% |
Caching is automatic — you don't need to configure anything. It's most effective when:
Consider a typical chatbot with a 2,000-token system prompt handling 1,000 requests per day:
That's a $0.30/day saving on system prompts alone. Scale that to larger prompts and higher volumes, and caching becomes one of the most significant cost levers available.
For applications with large, static context (like RAG systems that prepend retrieved documents), the savings compound quickly. A 100K-token context that's 80% cached drops from 0.02perrequesttoroughly0.02 per request to roughly 0.008.
Grok's API supports several built-in tools that extend the model's capabilities. These are billed per invocation, separate from token costs:
| Tool | Price | Description |
|---|---|---|
| Web Search | $5.00 / 1,000 calls | Real-time web search results |
| X Search | $5.00 / 1,000 calls | Search posts on X (Twitter) |
| Code Execution | $5.00 / 1,000 calls | Sandboxed code interpreter |
| File Attachments | $10.00 / 1,000 calls | Process uploaded files |
| Collections | $2.50 / 1,000 calls | Search curated document collections |
These costs are modest individually, but they add up in agentic workflows where the model might invoke multiple tools per turn. An agent that performs 3 web searches and 2 code executions per request adds $0.025 in tool costs on top of token fees.
xAI offers a Batch API that processes requests asynchronously at half the standard price:
| Model | Standard Input | Batch Input | Standard Output | Batch Output |
|---|---|---|---|---|
| Grok 4.1 Fast | $0.20 / MTok | $0.10 / MTok | $0.50 / MTok | $0.25 / MTok |
| Grok 4 | $3.00 / MTok | $1.50 / MTok | $15.00 / MTok | $7.50 / MTok |
The Batch API is ideal for workloads that don't require real-time responses:
The trade-off is latency. Batch requests are queued and processed when capacity is available, typically completing within minutes to hours rather than seconds. For any workflow where you can tolerate async processing, the 50% discount is essentially free money.
The Batch API discount and prompt caching can stack. If your batch requests share common prefixes (which they often do), you get:
A cached batch input token on Grok 4.1 Fast costs just $0.025/MTok — that's 87.5% cheaper than the standard rate.
Crazyrouter is an API gateway that provides access to Grok 4.1 (and 200+ other models) at 90% of official pricing — an automatic 10% discount on every request.
| Model | Official Input | Crazyrouter Input | Official Output | Crazyrouter Output |
|---|---|---|---|---|
| Grok 4.1 Fast | $0.20 / MTok | $0.18 / MTok | $0.50 / MTok | $0.45 / MTok |
| Grok 4 | $3.00 / MTok | $2.70 / MTok | $15.00 / MTok | $13.50 / MTok |
Crazyrouter uses the OpenAI-compatible API format, so switching is a one-line change. Just update your base_url:
Python (OpenAI SDK):
cURL:
Beyond the 10% discount:
Let's walk through three practical scenarios to see what Grok 4.1 Fast actually costs in production.
Setup: 3,000-token system prompt, average 1,500 tokens per user message, 800-token responses, 10,000 conversations/day.
| Component | Tokens | Cost |
|---|---|---|
| System prompt (cached) | 3K × 10,000 = 30M | 30 × 0.05=0.05 = 1.50 |
| User messages | 1.5K × 10,000 = 15M | 15 × 0.20=0.20 = 3.00 |
| Responses | 0.8K × 10,000 = 8M | 8 × 0.50=0.50 = 4.00 |
| Daily total | $8.50 | |
| Monthly total | ~$255 | |
| With Crazyrouter (10% off) | ~$229.50 |
For a chatbot handling 10,000 conversations daily, that's remarkably affordable.
Setup: Processing 500 legal documents/day, average 50K tokens each, 5K-token summaries, using Batch API.
| Component | Tokens | Cost (Batch) |
|---|---|---|
| Document input | 50K × 500 = 25B... 25,000M | Wait — let's recalculate: 50K × 500 = 25M tokens |
| Summaries output | 5K × 500 = 2.5M | 2.5 × 0.25=0.25 = 0.625 |
| Daily total | $3.125 | |
| Monthly total | ~$94 | |
| With Crazyrouter (10% off) | ~$84.50 |
Using the Batch API cuts costs in half, and the 2M context window means even the longest legal documents fit in a single request without chunking.
Setup: Developer tool that analyzes codebases, uses web search and code execution. 200 sessions/day, average 100K context tokens, 10K output tokens, 3 tool calls per session.
| Component | Tokens / Calls | Cost |
|---|---|---|
| Code context (80% cached) | 20K fresh × 200 = 4M | 4 × 0.20=0.20 = 0.80 |
| Code context (cached) | 80K × 200 = 16M | 16 × 0.05=0.05 = 0.80 |
| Output | 10K × 200 = 2M | 2 × 0.50=0.50 = 1.00 |
| Web Search | 200 × 1 = 200 calls | 200 × 0.005=0.005 = 1.00 |
| Code Execution | 200 × 2 = 400 calls | 400 × 0.005=0.005 = 2.00 |
| Daily total | $5.60 | |
| Monthly total | ~$168 | |
| With Crazyrouter (10% off) | ~$151 |
Even with tool usage, the total cost stays well under $200/month for a fairly active coding assistant.
How does Grok 4.1 Fast stack up against other budget-friendly frontier models?
| Feature | Grok 4.1 Fast | GPT-5-mini | Gemini 2.5 Flash |
|---|---|---|---|
| Input Price | $0.20 / MTok | $0.40 / MTok | $0.15 / MTok |
| Output Price | $0.50 / MTok | $1.60 / MTok | $0.60 / MTok |
| Context Window | 2,000,000 | 1,047,576 | 1,048,576 |
| Cached Input | $0.05 / MTok | $0.10 / MTok | $0.0375 / MTok |
| Batch Discount | 50% off | 50% off | Varies |
| Built-in Tools | Web, X, Code, Files | Web, Code | Google Search, Code |
Grok 4.1 Fast wins on:
Gemini 2.5 Flash wins on:
GPT-5-mini wins on:
For most cost-conscious developers, Grok 4.1 Fast and Gemini 2.5 Flash are the top contenders. Grok's edge is the 2M context window and cheaper output tokens; Gemini's edge is marginally cheaper input. Through Crazyrouter, you can access all three through a single API and switch between them as needed.
Grok 4.1 Fast is absurdly cheap. At 0.20/0.20/0.50 per MTok, it's one of the most cost-effective frontier models available. Most production workloads will cost under $300/month.
The 2M context window is a game-changer. It eliminates the need for complex chunking strategies and enables use cases that simply weren't practical before — full codebase analysis, entire book processing, long-running agent sessions.
Caching saves 75% automatically. No configuration needed. Any repeated prefix (system prompts, few-shot examples, conversation history) gets cached at 0.05/MTokinsteadof0.05/MTok instead of 0.20/MTok.
Batch API halves your costs for async work. If you don't need real-time responses, the Batch API at 0.10/0.10/0.25 per MTok is a no-brainer.
Tool costs are modest but worth tracking. At 0.005–0.005–0.01 per invocation, tools are cheap individually but can add up in agentic workflows with many calls per session.
Crazyrouter adds another 10% off everything. One API key, 200+ models, OpenAI-compatible format, and automatic savings. It's the easiest optimization you can make.
Stack your discounts. Caching + Batch API + Crazyrouter can reduce your effective cost by over 90% compared to standard Grok 4 pricing.
Ready to start building with Grok 4.1 Fast at discounted rates?
https://crazyrouter.com/v1grok-4-1-fast (or grok-4 for the premium tier)No minimum spend. No commitments. Pay only for what you use, and save 10% on every token.
👉 Start using Grok 4.1 Fast on Crazyrouter →
Last updated: April 27, 2026
Disclaimer: Pricing information is based on publicly available data from xAI as of the date above. Prices may change without notice. Crazyrouter pricing reflects a 10% discount off official xAI API rates. Always verify current pricing on the official xAI documentation and crazyrouter.com before making purchasing decisions. This article is for informational purposes only and does not constitute financial advice.
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