Grok 4.1 Fast vs Grok 4.20

Compare xAI and xAI AI models

xAI

Grok 4.1 Fast

xAI

Grok 4.20

Try xAI →

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

Grok 4.1 Fast

Per Request:$0.000450

Daily:$0.045

Monthly:$1.35

Yearly:$16.425

Grok 4.20

Per Request:$0.005000

Daily:$0.50

Monthly:$15.00

Yearly:$182.50

Cost Differences

+$0.004550

Per Request

+$0.455

Daily

+$13.65

Monthly

+$166.075

Yearly

Grok 4.20 costs more than Grok 4.1 Fast

Feature Comparison

Feature	Grok 4.1 Fast	Grok 4.20
Provider	xAI	xAI
Input Price	$0.20/1M tokens	$2.00/1M tokens
Output Price	$0.50/1M tokens	$6.00/1M tokens
Context Window	2,000,000 tokens	2,000,000 tokens
Max Output	131,072 tokens	131,072 tokens
Category	efficient	reasoning
Capabilities	textreasoningcode	textvisionreasoningcode
Release Date	1/15/2026	2/17/2026

Grok 4.1 Fast vs Grok 4.20: Which Should You Choose?

Choosing between Grok 4.1 Fast and Grok 4.20 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 — 90% cheaper than Grok 4.20.

These models target different tiers: Grok 4.1 Fast is a efficient model while Grok 4.20 is reasoning. This means they're optimized for different workloads. Grok 4.20 targets more demanding workloads, while Grok 4.1 Fast provides a cost-effective option for everyday tasks.

Output costs matter too. Grok 4.1 Fast charges $0.50/1M output tokens vs $6.00 for Grok 4.20. 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 4.20 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 4.1 Fast when:

• Budget is a primary concern
• You're already using xAI's API ecosystem
• You're running high-volume, latency-sensitive workloads

Choose Grok 4.20 when:

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

Try Different Scenarios

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

Grok 4.1 Fast (xAI)

Cost Calculator

Provider

Model

Input Tokens

Output Tokens

Requests/Day

Select a provider and model to see costs

Grok 4.20 (xAI)

Cost Calculator

Provider

Model

Input Tokens

Output Tokens

Requests/Day

Select a provider and model to see costs

Start using Grok 4.1 Fast today

Start using Grok 4.20 today

Frequently Asked Questions

Which is cheaper, Grok 4.1 Fast or Grok 4.20?▼

Grok 4.1 Fast is cheaper for input tokens at $0.20 per million tokens vs $2.00 for Grok 4.20 — that's 90% savings on input costs.

What is the context window difference between Grok 4.1 Fast and Grok 4.20?▼

Grok 4.1 Fast supports 2,000,000 tokens while Grok 4.20 supports 2,000,000 tokens — a difference of 0 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 2,000,000 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 4.1 Fast costs about $1.35/month and Grok 4.20 costs about $15.00/month. Overall, Grok 4.1 Fast has lower combined input + output rates ($0.20 in, $0.50 out) vs Grok 4.20.