Grok 3 vs Grok 4.1 Fast

Compare xAI and xAI AI models

xAI

Grok 3

xAI

Grok 4.1 Fast

Try xAI →

Cost Comparison (1000 input + 500 output tokens, 100 requests/day)

Grok 3

Per Request:$0.0105

Daily:$1.05

Monthly:$31.50

Yearly:$383.25

Grok 4.1 Fast

Per Request:$0.000450

Daily:$0.045

Monthly:$1.35

Yearly:$16.425

Cost Differences

$0.01005

Per Request

$1.005

Daily

$30.15

Monthly

$366.825

Yearly

Grok 4.1 Fast costs less than Grok 3

Feature Comparison

Feature	Grok 3	Grok 4.1 Fast
Provider	xAI	xAI
Input Price	$3.00/1M tokens	$0.20/1M tokens
Output Price	$15.00/1M tokens	$0.50/1M tokens
Context Window	131,072 tokens	2,000,000 tokens
Max Output	131,072 tokens	131,072 tokens
Category	flagship	efficient
Capabilities	textvisionreasoningcode	textreasoningcode
Release Date	2/17/2025	1/15/2026

Grok 3 vs Grok 4.1 Fast: Which Should You Choose?

Choosing between Grok 3 and Grok 4.1 Fast depends on your priorities: cost efficiency, context length, or raw capability. Grok 4.1 Fast is the more affordable option at $0.20/1M input tokens — 93% cheaper than Grok 3. Meanwhile, Grok 4.1 Fast offers a significantly larger context window at 2,000,000 tokens vs 131,072 for Grok 3.

These models target different tiers: Grok 3 is a flagship model while Grok 4.1 Fast is efficient. This means they're optimized for different workloads. Grok 3 is built for complex tasks that require deeper reasoning, while Grok 4.1 Fast offers better value for routine operations.

Output costs matter too. Grok 3 charges $15.00/1M output tokens vs $0.50 for Grok 4.1 Fast. For generation-heavy workloads (content creation, code generation, summarization), output pricing often dominates your bill. Grok 4.1 Fast has the edge here at $0.50/1M output tokens.

Multimodal capabilities: Grok 3 supports vision (image inputs) while Grok 4.1 Fast is text-only. If your application needs image understanding, this narrows your choice.

Best Use Cases

Choose Grok 3 when:

• You need more capabilities (vision)
• You're already using xAI's API ecosystem

Choose Grok 4.1 Fast when:

• Budget is a primary concern
• You need a larger context window (2,000,000 tokens)
• You're already using xAI's API ecosystem
• You're running high-volume, latency-sensitive workloads

Try Different Scenarios

Use the calculator below to see how costs change with different usage patterns

Grok 3 (xAI)

Cost Calculator

Provider

Model

Input Tokens

Output Tokens

Requests/Day

Select a provider and model to see costs

Grok 4.1 Fast (xAI)

Cost Calculator

Provider

Model

Input Tokens

Output Tokens

Requests/Day

Select a provider and model to see costs

Start using Grok 3 today

Start using Grok 4.1 Fast today

Frequently Asked Questions

Which is cheaper, Grok 3 or Grok 4.1 Fast?▼

Grok 4.1 Fast is cheaper for input tokens at $0.20 per million tokens vs $3.00 for Grok 3 — that's 93% savings on input costs.

What is the context window difference between Grok 3 and Grok 4.1 Fast?▼

Grok 3 supports 131,072 tokens while Grok 4.1 Fast supports 2,000,000 tokens — a difference of 1,868,928 tokens in favor of Grok 4.1 Fast.

Which model is better for AI Agent / Agentic Workflows?▼

Both models support text, code, reasoning. For ai agent / agentic workflows, Grok 4.1 Fast is the lower-cost option, while Grok 4.1 Fast offers a larger context window (2,000,000 vs 131,072 tokens). Choose Grok 4.1 Fast for budget sensitivity or Grok 4.1 Fast for longer context tasks.

Which model has better overall pricing for heavy usage?▼

At 100 requests/day with 1,000 input and 500 output tokens each, Grok 3 costs about $31.50/month and Grok 4.1 Fast costs about $1.35/month. Overall, Grok 4.1 Fast has lower combined input + output rates ($0.20 in, $0.50 out) vs Grok 3.