Grok 4.3 beta is now available to Heavy subscribers! Musk: The real flagship version’s initial training will be completed in 5 days.

Grok 4.3 beta has been available to SuperGrok Heavy subscribers ($300/month) since April 17. User Mark Kretschmann posted on the 18th that this version features 1T parameters, doubling the capacity of Grok 4.20. Elon Musk immediately clarified in the same tweet that the true 1T flagship model still has 5 days remaining to complete initial training.
(Background: SpaceX merged with xAI and lost nearly $5 billion! Burning $1 billion worth of compute power every month.)
(Additional context: Musk showcased the completion of AI5 chip design, rebooted Dojo3, and Tesla AI6 is under development.)

Grok 4.3 beta appears in the Grok.com dropdown menu with “Early Access” displayed. Only SuperGrok Heavy subscribers paying $300 per month can enable it; regular $30 SuperGrok plans can only see it.

This version can operate with PDF, PPT, Excel generation, as well as video input and enhanced reasoning. The context window has jumped from 128K tokens in the old version to 2M tokens (!!).

This is still 0.5T, but a more recent training checkpoint.

1T model is ~5 days away from finishing initial training. Will be a major step change improvement in coding, long context, and skills.

The SpaceXAI model factory is finally working. Should be an improved base model…

— Elon Musk (@elonmusk) April 18, 2026

Today, user Mark Kretschmann on X stated that this version features 1T parameters, twice that of Grok 4.20, with significantly longer training times.

A few hours later, Musk responded with clarification: “Current Grok 4.3 (beta) is still 0.5T, just with an updated training checkpoint.”

The 1T flagship version has 5 days remaining to complete initial training.

In his clarification, Musk also mentioned that this version will bring massive upgrades in coding, long context, and various skills, reaching step function level improvements.

The SpaceXAI factory is simultaneously running 7 models, with a maximum scale burning up to 10T.

Musk revealed that the SpaceXAI Colossus 2 model factory is operational. Currently training includes: two 1T models, two 1.5T models, one 6T, one 10T, and the Imagine V2 image model. The pre-training for the 10T model is expected to take another two months.

Grok Computer is also launched simultaneously.

Alongside Grok 4.3 beta, Grok Computer has been released—an autonomous PC agent from xAI capable of operating applications, filling out forms, and executing multi-step desktop tasks. Grok 4.3 serves as the reasoning engine, while Grok Computer is the action layer. Some wider beta access has been granted to certain SuperGrok accounts.