Grok 4.1 Fast Reasoning
API model name: grok-4.1-fast-reasoning
Grok 4.1 Fast Reasoning is xAI's chat model, served on the Api.Airforce unified API. It has a 2M-token context window. Beyond text, it accepts image as input. Capabilities include Vision, Tool calling, Reasoning, Prompt caching. It is priced at $0.50 per million input tokens and $0.50 per million output tokens. That is below the provider's $0.20 official input rate. Knowledge cutoff: 2025-09. Access it through the OpenAI-compatible API with one key, alongside 100+ other models on Api.Airforce.
Pricing
Api.Airforce price vs. the provider's official rate.
Specifications
- Provider
- xAI
- Type
- chat model
- Context window
- 2M tokens
- Max output
- 33K tokens
- Knowledge cutoff
- 2025-09
- Input
- text, image
- Output
- text
- Prompt caching
- Supported
Capabilities
Benchmarks
Independent evaluations and measured speed from Artificial Analysis.
Source: Benchmark data by Artificial Analysis (artificialanalysis.ai)
What is Grok 4.1 Fast Reasoning used for?
- Chatbots & assistants — conversational AI, drafting, summarizing and Q&A.
- Image understanding — analyze photos, screenshots, charts and scanned documents.
- Agents & automation — function calling and tool use for multi-step workflows.
- Complex reasoning — math, coding and step-by-step problem solving.
- Long-context tasks — process entire documents or codebases in a single prompt.
- Real-time experiences — stream tokens for responsive chat and apps.
Grok 4.1 Fast Reasoning vs. similar models
| Model | Intelligence | Context | Input / 1M | Output / 1M |
|---|---|---|---|---|
| Grok 4.1 Fast Reasoning | 38.6 | 2M | $0.50 | $0.50 |
| Grok 2 Vision | — | — | $3.12 | $15.57 |
| Grok 3 | — | — | $0.45 | $2.25 |
| Grok 3 Deepsearch | — | — | $0.42 | $2.13 |
Prices are Api.Airforce pay-as-you-go rates per 1M tokens. Context is the maximum input length.
Related models
Grok 4.1 Fast Reasoning — frequently asked questions
- How much does Grok 4.1 Fast Reasoning cost?
- Grok 4.1 Fast Reasoning is billed pay-as-you-go at $0.50 per 1M input tokens and $0.50 per 1M output tokens. There is no subscription — you only pay for what you use.
- What is the context window of Grok 4.1 Fast Reasoning?
- Grok 4.1 Fast Reasoning supports a context window of up to 2M tokens. It can return up to 33K tokens in a single response.
- What can Grok 4.1 Fast Reasoning do?
- Grok 4.1 Fast Reasoning supports Vision, Tool calling, Reasoning, Prompt caching.
- Is Grok 4.1 Fast Reasoning free to use?
- Grok 4.1 Fast Reasoning is a paid, pay-as-you-go model — no subscription, you are only charged for usage.
- How do I use Grok 4.1 Fast Reasoning via the API?
- Grok 4.1 Fast Reasoning is OpenAI-compatible. Point any OpenAI SDK at https://api.airforce/v1 and pass the model ID grok-4.1-fast-reasoning with your Api.Airforce API key.
- Who makes Grok 4.1 Fast Reasoning?
- Grok 4.1 Fast Reasoning is xAI's chat model, served through the unified Api.Airforce gateway alongside 100+ other models.
Use Grok 4.1 Fast Reasoning via the API
OpenAI-compatible — point any OpenAI SDK at https://api.airforce/v1 and pass grok-4.1-fast-reasoning as the model.
curl https://api.airforce/v1/chat/completions \
-H "Authorization: Bearer $AIRFORCE_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "grok-4.1-fast-reasoning",
"messages": [{ "role": "user", "content": "Hello!" }]
}'from openai import OpenAI
client = OpenAI(base_url="https://api.airforce/v1", api_key="$AIRFORCE_API_KEY")
r = client.chat.completions.create(
model="grok-4.1-fast-reasoning",
messages=[{"role": "user", "content": "Hello!"}],
)
print(r.choices[0].message.content)import OpenAI from "openai";
const client = new OpenAI({ baseURL: "https://api.airforce/v1", apiKey: process.env.AIRFORCE_API_KEY });
const r = await client.chat.completions.create({
model: "grok-4.1-fast-reasoning",
messages: [{ role: "user", content: "Hello!" }],
});
console.log(r.choices[0].message.content);