Grok 4.3

Grok 4.3 is a lower-cost xAI model with a 1M-token context window and configurable reasoning that defaults to low effort. xAI points users of the Grok 4 Fast and Grok 4.1 Fast models, retired on May 15, 2026, to Grok 4.3 as their replacement.

By xAIReleased April 2026Data checked October 10, 2026

CurrentClosedEfficient

Specifications

Context window: 1Mabout 750,000 words, or 1,500 pages
Max output: Not published
Input price: $1.25per 1M tokens
Output price: $2.50per 1M tokens
Cached input: $0.20per 1M tokens
Weights: ClosedProprietary
Parameters: Undisclosed
Input types: Text, Images
Output types: Text
Reasoning mode: Yes
Tool calling: Yes
Released: Apr 2026Current

Rates for prompts under 200K tokens; at 200K or more, $2.50 input, $0.40 cached and $5 output. Batch API 20% off. Max output is not stated by xAI.

What it costs in practice

Workload	Monthly cost at list price
Support chatbot30,000 conversations a month, 2,000 input and 400 output tokens each	$105
Document summaries2,000 documents a month, 12,000 input and 800 output tokens each	$34
Coding agent1,000 tasks a month, 60,000 input and 6,000 output tokens each	$90

Standard rates, no caching or batch discounts. Run your own numbers.

Strengths

$1.25 input and $2.50 output per million tokens
1M-token context window
Batch API support at a 20% discount

Trade-offs to weigh

Rates double for prompts of 200K tokens or more
Default reasoning effort is low, so harder tasks may need a higher setting

Where it fits

xAI positions Grok 4.3 for:

high volumeagentslong documentsdata extraction

Where you can use it

API
OpenRouter

Alternatives to consider

Model	Tier	Context	Input / output per 1M
Qwen3.8-27BAlibaba (Qwen)	Efficient	256K	$0.80 / $4	Compare
Gemini 3.5 Flash-LiteGoogle	Efficient	1M	$0.30 / $2.50	Compare
SonarPerplexity	Efficient	—	$0.25 / $2.50	Compare
Gemini 3.1 Flash-LiteGoogle	Efficient	1M	$0.25 / $1.50	Compare

Frequently asked questions

How much does Grok 4.3 cost?

Grok 4.3 lists at $1.25 per million input tokens and $2.50 per million output tokens, with cached input at $0.20 (checked October 10, 2026). Rates for prompts under 200K tokens; at 200K or more, $2.50 input, $0.40 cached and $5 output. Batch API 20% off. Max output is not stated by xAI. Confirm current rates on the provider's pricing page before you commit.

What is the context window of Grok 4.3?

Grok 4.3 accepts up to 1,000,000 tokens of context (about 750,000 words, or 1,500 pages). Long prompts cost more and can be slower, so most apps send only what the task needs.

Is Grok 4.3 open source?

No. Grok 4.3 is a proprietary model from xAI; its weights aren't published. You can use it through the xAI API and through OpenRouter.

What is Grok 4.3 best for?

xAI positions Grok 4.3 for high volume, agents, long documents, data extraction. It accepts text, images as input, has a reasoning (thinking) mode and supports tool calling. Test it on a sample of your own tasks before you choose it for production.

Sources

Facts checked against these pages on October 10, 2026. Spot an error? Tell us.

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