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Model Comparison

Claude Sonnet 4.5 vs Phi 4 ReasoningWhich is better in 2026?

Claude Sonnet 4.5 significantly outperforms across most benchmarks.

Verdict: Claude Sonnet 4.5 vs Phi 4 Reasoning — which is better?

Claude Sonnet 4.5 (by Anthropic) and Phi 4 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.

Claude Sonnet 4.5 outperforms in 2 benchmarks (AIME 2025, GPQA), while Phi 4 Reasoning is better at 0 benchmarks. Claude Sonnet 4.5 significantly outperforms across most benchmarks.

Choose Claude Sonnet 4.5 if…

  • you want the strongest raw capability — it leads on 2 of 2 shared benchmarks
  • you want the most recent training data — it shipped Sep 2025

Choose Phi 4 Reasoning if…

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

Performance Benchmarks

Comparative analysis across standard metrics

2 benchmarks

Claude Sonnet 4.5 outperforms in 2 benchmarks (AIME 2025, GPQA), while Phi 4 Reasoning is better at 0 benchmarks.

Claude Sonnet 4.5 significantly outperforms across most benchmarks.

Fri Aug 07 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only Claude Sonnet 4.5 specifies input context (200,000 tokens). Only Claude Sonnet 4.5 specifies output context (64,000 tokens).

Anthropic
Claude Sonnet 4.5
Input200,000 tokens
Output64,000 tokens
Microsoft
Phi 4 Reasoning
Input- tokens
Output- tokens
Fri Aug 07 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Claude Sonnet 4.5 supports multimodal inputs, whereas Phi 4 Reasoning does not.

Claude Sonnet 4.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Claude Sonnet 4.5

Text
Images
Audio
Video

Phi 4 Reasoning

Text
Images
Audio
Video

License

Usage and distribution terms

Claude Sonnet 4.5 is licensed under a proprietary license, while Phi 4 Reasoning uses MIT.

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

Claude Sonnet 4.5

Proprietary

Closed source

Phi 4 Reasoning

MIT

Open weights

Release Timeline

When each model was launched

Claude Sonnet 4.5 was released on 2025-09-29, while Phi 4 Reasoning was released on 2025-04-30.

Claude Sonnet 4.5 is 5 months newer than Phi 4 Reasoning.

Claude Sonnet 4.5

Sep 29, 2025

10 months ago

5mo newer
Phi 4 Reasoning

Apr 30, 2025

1.3 years ago

Knowledge Cutoff

When training data ends

Claude Sonnet 4.5 has a knowledge cutoff of 2025-01-31, while Phi 4 Reasoning has a cutoff of 2025-03-01.

Phi 4 Reasoning has more recent training data (up to 2025-03-01), making it potentially better informed about events through that date compared to Claude Sonnet 4.5 (2025-01-31).

Claude Sonnet 4.5

Jan 2025

Phi 4 Reasoning

Mar 2025

2 mo newer

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Anthropic
Larger context window (200,000 tokens)
Supports multimodal inputs
Higher AIME 2025 score (87.0% vs 62.9%)
Higher GPQA score (83.4% vs 65.8%)
Microsoft
Has open weights

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Claude Sonnet 4.5 and Phi 4 Reasoning side-by-side, then vote on the output you prefer.

Claude Sonnet 4.5
✓ Preferred
Phi 4 Reasoning
Open in Playground
AI Model Comparison Table
Feature
Anthropic
Claude Sonnet 4.5
Microsoft
Phi 4 Reasoning

FAQ

Common questions about Claude Sonnet 4.5 vs Phi 4 Reasoning.

Which is better, Claude Sonnet 4.5 or Phi 4 Reasoning?

Claude Sonnet 4.5 significantly outperforms across most benchmarks. Claude Sonnet 4.5 is made by Anthropic and Phi 4 Reasoning is made by Microsoft. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Claude Sonnet 4.5 compare to Phi 4 Reasoning in benchmarks?

Claude Sonnet 4.5 scores MMMLU: 89.1%, AIME 2025: 87.0%, TAU-bench Retail: 86.2%, GPQA: 83.4%, MMMUval: 77.8%. Phi 4 Reasoning scores FlenQA: 97.7%, HumanEval+: 92.9%, IFEval: 83.4%, OmniMath: 76.6%, AIME 2024: 75.3%.

What are the context window sizes for Claude Sonnet 4.5 and Phi 4 Reasoning?

Claude Sonnet 4.5 supports 200K tokens and Phi 4 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 Claude Sonnet 4.5 and Phi 4 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 Claude Sonnet 4.5 and Phi 4 Reasoning?

Claude Sonnet 4.5 is developed by Anthropic and Phi 4 Reasoning is developed by Microsoft.

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