Grok 4.1 Fast — xAI | Modeldex

Grok 4.1 Fast

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Grok 4.1 Fast is xAI's best agentic tool calling model that shines in real-world use cases like customer support and deep research. 2M context window. Reasoning can be enabled/disabled using...

VisionLong contextBudget

API release

Nov 19, 2025(5 months ago)

Not enough benchmark coverage yet for an Intelligence Index — needs at least 3 results across 2 categories.

Overview

Grok 4.1 Fast is xAI's best agentic tool calling model that shines in real-world use cases like customer support and deep research. 2M context window. Reasoning can be enabled/disabled using...

History

Grok 4.1 Fast became available via the xAI API on 2025-11-19.

Training & availability

xAI has not released the underlying model weights — access is via their hosted API only.

Capabilities

Context window: 2.0M tokens.
Input modalities: text, image, file.

Recommended for: vision, long-context, cheap.

Pricing

Input: $0.2000 per 1M tokens
Output: $0.5000 per 1M tokens

Use the cost calculator above to estimate monthly spend for your workload.

Quick start

Minimal example using the OpenRouter API. Copy, paste, replace the key.

from openai import OpenAI

client = OpenAI(
    base_url="https://openrouter.ai/api/v1",
    api_key="sk-or-...",
)
resp = client.chat.completions.create(
    model="xai/grok-4-1-fast",
    messages=[{"role": "user", "content": "Explain quantum computing in one sentence."}],
)
print(resp.choices[0].message.content)

Cost calculator

Estimate your monthly bill. Presets are typical workload sizes.

Input tokens / month5.0M

@ $0.2/1M

Output tokens / month2.0M

@ $0.5/1M

Input cost

5.0M × $0.2/1M

Output cost

2.0M × $0.5/1M

Total / month

$24 / year

Providers & performance

1 provider

Multi-provider inference routes for this model — sorted by throughput. Latency is time-to-first-token; throughput is output tokens per second. Data from OpenRouter, measured over the last 30 minutes.

Provider	Throughput	Latency (TTFT)	Input $ / 1M	Output $ / 1M	Context	Quant	Supports
xAI	103tok/s	641ms	$0.2	$0.5	2.0M	—	tools · json

Integrations & tooling support

Tool calling: Not supported
Structured outputs: Not supported

Price vs quality

Not enough data

This model has no benchmark scores recorded yet.

Community ratings

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