xAI Grok 4.1 Fast vs xAI Grok‑1.5 — side-by-side specs.
xAI Grok 4.1 Fast | xAI Grok‑1.5 | |
|---|---|---|
| Overview | ||
| Company | xAI | xAI |
| Release date | Nov 19 2025 | Mar 29 2024 |
| Model type | — | — |
| Open source | No | No |
| Specifications | ||
Parameters | — | — |
Context window | — | — |
| Benchmarks | ||
| Timeline | ||
| Release gap | Grok‑1.5 shipped 600 days before Grok 4.1 Fast | |
Grok 4.1 Fast and Grok‑1.5 don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Grok‑1.5 shipped 600 days before Grok 4.1 Fast, so benchmark comparisons should account for the intervening progress.
Published specifications for these two models are limited — see each model page for the latest details.
Direct benchmark comparisons are unavailable — Grok 4.1 Fast and Grok‑1.5 don't publish scores on any of the same benchmarks.