Grok-4 Fast Reasoning vs Hy4 preview
Comparing Grok-4 Fast Reasoning and Hy4 preview across benchmarks, pricing, and capabilities.
xAI · Tencent · Updated for 2026
Which is better?
Grok-4 Fast Reasoning and Hy4 preview trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose Grok-4 Fast Reasoning
- you want predictable pricing at $0.20/M input and $0.50/M output
Choose Hy4 preview
- you want the most recent training data — it shipped Aug 2026
- you need open weights you can self-host or fine-tune
At a glance
The differences that matter most.
Individual benchmarks
0 reported for Grok-4 Fast Reasoning · 32 for Hy4 preview
Grok-4 Fast Reasoning and Hy4 previewdon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.
Human preference
Blind head-to-head votes and playground preference scores
Context Window
Maximum input and output token capacity
Only Grok-4 Fast Reasoning specifies input context (2,000,000 tokens). Only Grok-4 Fast Reasoning specifies output context (30,000 tokens).
Input capabilities
Documented input modalities across available providers
Grok-4 Fast Reasoning supports multimodal inputs, whereas Hy4 preview does not.
Grok-4 Fast Reasoning can handle both text and other forms of data like images, making it suitable for multimodal applications.
Grok-4 Fast Reasoning
Hy4 preview
License
Usage and distribution terms
Grok-4 Fast Reasoning is licensed under a proprietary license, while Hy4 preview uses Apache 2.0.
License differences may affect how you can use these models in commercial or open-source projects.
Proprietary
Closed source
Apache 2.0
Open weights
Release Timeline
When each model was launched
Grok-4 Fast Reasoning was released on 2025-08-28, while Hy4 preview was released on 2026-08-28.
Hy4 preview is 12 months newer than Grok-4 Fast Reasoning.
Aug 28, 2025
1.0 years ago
Aug 28, 2026
6 days ago
1.0yr newerKnowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Outputs Comparison
Judge for yourself.
Run your own prompts against Grok-4 Fast Reasoning and Hy4 preview side-by-side, then vote on the output you prefer.
FAQ
Common questions about Grok-4 Fast Reasoning vs Hy4 preview.