Grok 4.21 release date
ForecastxAIlanguage model
Grok 4.21 has not been announced. Based on how often xAI ships new versions, our forecast is that it arrives around November 8, 2026, probably between October 30, 2026 and December 2, 2026.
The forecast
| Most likely | November 8, 2026 |
|---|---|
| Window | October 30, 2026 to December 2, 2026 |
| Chance it arrives in that window | About 54% |
| Follows | Grok 4.20 (out March 31, 2026) |
| Based on | 3 earlier gaps between versions |
How we got this
xAI is the maker of Grok 4.20. We look at the gaps between its earlier versions (Grok 4.5, 2026-07-08; Grok 4.6, 2026-08-12; Grok 4.7, 2026-09-21; Grok 4.20, 2026-03-31) and project the next one. It is a guess from a pattern, not news: the maker has not said Grok 4.21 exists. This page turns into the launch page, with price and facts, as soon as the model shows up on OpenRouter, Hugging Face or GitHub.
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Predicted automatically by Modelcast. Not affiliated with xAI.