Grok 4.8

Estimated release

Oct 20, 2026

Late Oct 2026

Details

Status: Musk says pre-training finished mid-September and RL is under way; xAI has not announced a date
Current model: Grok 4.7, 46.4 on the Intelligence Index, released Sep 21, 2026 ()
Projected score: About 49.4 (+3)
Typical cycle: About 32 days between releases

2.5 trillion parameter model on xAI's entirely new C++ training stack, pre-training completed week of Sept 14 and moving into reinforcement learning
Beats the 2.1T JAX-trained predecessor despite mistakes corrected midway; a 3T successor is already planned
Musk named Grok 4.9 as the Astra/Fable-class step and Grok 5 as the one after, so both are separate later releases
Continuation of the 4.7 pattern: same $2/$6 pricing, larger base model, longer RL run on a harder task mix
Grok 4.5 (Jul 8), 4.6 (Aug 12) and 4.7 (Sept 21) came 5 to 6 weeks apart, which points to late October

Source: Elon Musk X thread (Sept 14, 2026): Grok 4.8 at 2.5T params, new C++ stack, RL next