Model Comparison

Grok 4 Fast vs Phi 4 Mini ReasoningWhich is better in 2026?

Grok 4 Fast significantly outperforms across most benchmarks.

Verdict: Grok 4 Fast vs Phi 4 Mini Reasoning — which is better?

Grok 4 Fast (by xAI) and Phi 4 Mini Reasoning (by Microsoft) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.

Grok 4 Fast outperforms in 1 benchmarks (GPQA), while Phi 4 Mini Reasoning is better at 0 benchmarks. Grok 4 Fast significantly outperforms across most benchmarks.

Choose Grok 4 Fast if…

  • you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
  • you want the most recent training data — it shipped Aug 2025

Choose Phi 4 Mini Reasoning if…

  • you need open weights you can self-host or fine-tune
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Performance Benchmarks

Comparative analysis across standard metrics

1 benchmarks

Grok 4 Fast outperforms in 1 benchmarks (GPQA), while Phi 4 Mini Reasoning is better at 0 benchmarks.

Grok 4 Fast significantly outperforms across most benchmarks.

Tue Jun 16 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only Grok 4 Fast specifies input context (2,000,000 tokens). Only Grok 4 Fast specifies output context (30,000 tokens).

xAI
Grok 4 Fast
Input2,000,000 tokens
Output30,000 tokens
Microsoft
Phi 4 Mini Reasoning
Input- tokens
Output- tokens
Tue Jun 16 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Grok 4 Fast supports multimodal inputs, whereas Phi 4 Mini Reasoning does not.

Grok 4 Fast can handle both text and other forms of data like images, making it suitable for multimodal applications.

Grok 4 Fast

Text
Images
Audio
Video

Phi 4 Mini Reasoning

Text
Images
Audio
Video

License

Usage and distribution terms

Grok 4 Fast is licensed under a proprietary license, while Phi 4 Mini Reasoning uses MIT.

License differences may affect how you can use these models in commercial or open-source projects.

Grok 4 Fast

Proprietary

Closed source

Phi 4 Mini Reasoning

MIT

Open weights

Release Timeline

When each model was launched

Grok 4 Fast was released on 2025-08-28, while Phi 4 Mini Reasoning was released on 2025-04-30.

Grok 4 Fast is 4 months newer than Phi 4 Mini Reasoning.

Grok 4 Fast

Aug 28, 2025

9 months ago

4mo newer
Phi 4 Mini Reasoning

Apr 30, 2025

1.1 years ago

Knowledge Cutoff

When training data ends

Phi 4 Mini Reasoning has a documented knowledge cutoff of 2025-02-01, while Grok 4 Fast's cutoff date is not specified.

We can confirm Phi 4 Mini Reasoning's training data extends to 2025-02-01, but cannot make a direct comparison without Grok 4 Fast's cutoff date.

Grok 4 Fast

—

Phi 4 Mini Reasoning

Feb 2025

Outputs Comparison

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Key Takeaways

xAI
Larger context window (2,000,000 tokens)
Supports multimodal inputs
Higher GPQA score (85.7% vs 52.0%)
Microsoft
Has open weights

Detailed Comparison

AI Model Comparison Table
Feature
xAI
Grok 4 Fast
Microsoft
Phi 4 Mini Reasoning

FAQ

Common questions about Grok 4 Fast vs Phi 4 Mini Reasoning.

Which is better, Grok 4 Fast or Phi 4 Mini Reasoning?

Grok 4 Fast significantly outperforms across most benchmarks. Grok 4 Fast is made by xAI and Phi 4 Mini Reasoning is made by Microsoft. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Grok 4 Fast compare to Phi 4 Mini Reasoning in benchmarks?

Grok 4 Fast scores SimpleQA: 95.0%, HMMT 2025: 93.3%, AIME 2025: 92.0%, GPQA: 85.7%, LiveCodeBench: 80.0%. Phi 4 Mini Reasoning scores MATH-500: 94.6%, AIME: 57.5%, GPQA: 52.0%.

What are the context window sizes for Grok 4 Fast and Phi 4 Mini Reasoning?

Grok 4 Fast supports 2.0M tokens and Phi 4 Mini Reasoning supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Grok 4 Fast and Phi 4 Mini Reasoning?

Key differences include multimodal support (yes vs no), licensing (Proprietary vs MIT). See the full comparison above for benchmark-by-benchmark results.

Who makes Grok 4 Fast and Phi 4 Mini Reasoning?

Grok 4 Fast is developed by xAI and Phi 4 Mini Reasoning is developed by Microsoft.

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