Grok 4 Fast Reasoning

Grok 4 optimized for fast reasoning.

grok-4-fast-reasoning
STABLEModel DeactivatedGet StartedView uptime
2,000,000 context
Released July 9, 2025
Starting at $0.20/M input tokens (tiered)
Starting at $0.50/M output tokens (tiered)
Streaming
Vision
Tools
Reasoning
JSON Output
No ratings yetSign in to rate

Select Provider

All Providers for Grok 4 Fast Reasoning

LLM Gateway routes requests to the best providers that are able to handle your prompt size and parameters.

xAI
Context: 2M
Deactivated since May 15, 2026
Input
$0.2
/M tokens
Cache Read
$0.05
/M tokens
Output
$0.5
/M tokens
Tiered Pricing
IN
CACHED
OUT
≤128K tokens
$0.2
$0.05
$0.5
>128K tokens
$0.4
$0
$1
Get Started

Frequently asked questions

What is Grok 4 Fast Reasoning?

Grok 4 optimized for fast reasoning. You can access it through LLM Gateway's OpenAI-compatible API with automatic provider routing, fallback, and cost analytics.

How much does Grok 4 Fast Reasoning cost?

Pricing for Grok 4 Fast Reasoning on LLM Gateway starts at $0.20 per million input tokens and $0.50 per million output tokens, depending on the provider. The pricing table above always reflects the current per-provider rates.

What is the context length of Grok 4 Fast Reasoning?

Grok 4 Fast Reasoning supports a context window of up to 2,000,000 tokens on its largest provider deployment.

Which providers serve Grok 4 Fast Reasoning?

Grok 4 Fast Reasoning is served by xAI through LLM Gateway. Requests are automatically routed to the best available provider, with fallback when a provider has issues.

Does Grok 4 Fast Reasoning support tool calling and structured outputs?

Yes. Grok 4 Fast Reasoning supports both tool (function) calling and structured JSON outputs through LLM Gateway.

When was Grok 4 Fast Reasoning released?

Grok 4 Fast Reasoning was released on July 9, 2025.