xAI model product
Grok 4 Fast is a high-speed variant of Grok-4, optimized for faster inference while maintaining strong reasoning capabilities. It offers improved throughput and lower latency compared to the standard Grok-4 model.
Updated Aug 10, 2026. Default version: Grok 4 Fast
Structured fields from the published default version.
This profile uses the latest version under this unique model that has a calculated LLMBoard score. Arena and price are excluded.
Published benchmark records for the scored version Grok 4 Fast.
| SimpleQA | 0.9 | 2 | 46 | 97.8% | C | |
| LiveCodeBench | 0.8 | 9 | 73 | 88.9% | C | |
| HMMT 2025 | 0.9 | 13 | 33 | 62.5% | C | |
| AIME 2025 | 0.9 | 39 | 114 | 66.4% | C | |
| BrowseComp | 0.4 | 48 | 58 | 17.5% | C | |
| GPQA | 0.9 | 50 | 233 | 78.9% | C | |
| Humanity's Last Exam | 0.2 | 58 | 92 | 37.4% | C |
Preference and agent-evaluation signals from published Arena datasets.
The default version has no published Arena rows, or its source alias has not been resolved.
Official vendor API PAYG pricing is summarized first. The table then lists individual provider offerings without treating their minimum as the official price.
| ZenMux | x-ai/grok-4-fast | global | $0.20 | $0.50 | 2M |
Official prices use only the vendor's configured official Provider and positive standard USD PAYG rates. Third-party offers remain explicitly labeled.
All published versions linked to this unique model. The score columns identify the version used by the current overall ranking.
| Grok 4 Fast | 66.2 | N/A | 2M | 30K | No | Proprietary |
A concise description based on the published model registry.
Grok 4 Fast is a high-speed variant of Grok-4, optimized for faster inference while maintaining strong reasoning capabilities. It offers improved throughput and lower latency compared to the standard Grok-4 model.
Use the benchmark, Arena and pricing sections above as separate evidence. A missing field means the current data snapshot does not support that claim.
Data snapshot: 2026-08-07. Editorial model content is not available in the backend.
Open a comparison with the three ranked models immediately above and below this model.
Recommendations prioritize the same model type and family, then the closest published LLMBoard score.
Common questions about Grok 4 Fast.
Grok 4 Fast's default version was released on Aug 28, 2025.
No official standard PAYG price is currently available for Grok 4 Fast. The lowest tracked third-party offer starts at $0.20 input and $0.50 output via ZenMux.
Grok 4 Fast is published under xAI in the model registry.
The default version has a 2M token context window.
No. The default version is not marked as having publicly available weights.
1 published provider offerings are linked to the default version.
Nearby ranked alternatives include GPT-5.2, MiMo V2.5 Pro, Gemma 4 26B A4B.