Grok-4.1 Fast Reasoning vs Phi 4 Reasoning Plus
Comparing Grok-4.1 Fast Reasoning and Phi 4 Reasoning Plus across benchmarks, pricing, and capabilities.
xAI · Microsoft · Updated for 2026
Which is better?
Grok-4.1 Fast Reasoning and Phi 4 Reasoning Plus 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-4.1 Fast Reasoning
- you want the most recent training data — it shipped Nov 2025
Choose Phi 4 Reasoning Plus
- 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-4.1 Fast Reasoning · 11 for Phi 4 Reasoning Plus
Grok-4.1 Fast Reasoning and Phi 4 Reasoning Plusdon'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-4.1 Fast Reasoning specifies input context (2,000,000 tokens). Only Grok-4.1 Fast Reasoning specifies output context (30,000 tokens).
Input capabilities
Documented input modalities across available providers
Grok-4.1 Fast Reasoning supports multimodal inputs, whereas Phi 4 Reasoning Plus does not.
Grok-4.1 Fast Reasoning can handle both text and other forms of data like images, making it suitable for multimodal applications.
Grok-4.1 Fast Reasoning
Phi 4 Reasoning Plus
License
Usage and distribution terms
Grok-4.1 Fast Reasoning is licensed under a proprietary license, while Phi 4 Reasoning Plus uses MIT.
License differences may affect how you can use these models in commercial or open-source projects.
Proprietary
Closed source
MIT
Open weights
Release Timeline
When each model was launched
Grok-4.1 Fast Reasoning was released on 2025-11-17, while Phi 4 Reasoning Plus was released on 2025-04-30.
Grok-4.1 Fast Reasoning is 7 months newer than Phi 4 Reasoning Plus.
Nov 17, 2025
9 months ago
6mo newerApr 30, 2025
1.3 years ago
Knowledge Cutoff
When training data ends
Phi 4 Reasoning Plus has a documented knowledge cutoff of 2025-03-01, while Grok-4.1 Fast Reasoning's cutoff date is not specified.
We can confirm Phi 4 Reasoning Plus's training data extends to 2025-03-01, but cannot make a direct comparison without Grok-4.1 Fast Reasoning's cutoff date.
—
Mar 2025
Outputs Comparison
Judge for yourself.
Run your own prompts against Grok-4.1 Fast Reasoning and Phi 4 Reasoning Plus side-by-side, then vote on the output you prefer.
FAQ
Common questions about Grok-4.1 Fast Reasoning vs Phi 4 Reasoning Plus.