About Grok 4 Fast
Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Read more about the model on xAI's [news post](http://x.ai/news/grok-4-fast).
Reasoning can be enabled/disabled using the `reasoning` `enabled` parameter in the API. [Learn more in our docs](https://openrouter.ai/docs/use-cases/reasoning-tokens#controlling-reasoning-tokens)
Specifications
- Provider
- xAI
- Context Length
- 2,000,000 tokens
- Input Types
- text, image
- Output Types
- text
- Category
- Grok
- Added
- 9/19/2025
Benchmark Performance
How Grok 4 Fast compares to its closest rivals across industry benchmarks
Comprehensive comparison of AI models across intelligence, price, speed, and latency
Metric: Intelligence Index
#19
Nova 2.0 Pro Preview (medium)
62.0
#21
MiniMax-M2
61.0
#22
gpt-oss-120B (high)
61.0
#27
Nova 2.0 Lite (medium)
58.0
Frequently Asked Questions
Common questions about Grok 4 Fast