Model Comparison
Llama 3.1 405B Instruct vs Phi 4 ReasoningWhich is better in 2026?
Phi 4 Reasoning shows notably better performance in the majority of benchmarks.
Verdict: Llama 3.1 405B Instruct vs Phi 4 Reasoning — which is better?
Llama 3.1 405B Instruct (by Meta) 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.
Llama 3.1 405B Instruct outperforms in 1 benchmarks (IFEval), while Phi 4 Reasoning is better at 2 benchmarks (GPQA, MMLU-Pro). Phi 4 Reasoning shows notably better performance in the majority of benchmarks.
Choose Llama 3.1 405B Instruct if…
- you want predictable pricing at $0.89/M input and $0.89/M output
Choose Phi 4 Reasoning if…
- you want the strongest raw capability — it leads on 2 of 3 shared benchmarks
- you want the most recent training data — it shipped Apr 2025
Performance Benchmarks
Comparative analysis across standard metrics
Llama 3.1 405B Instruct outperforms in 1 benchmarks (IFEval), while Phi 4 Reasoning is better at 2 benchmarks (GPQA, MMLU-Pro).
Phi 4 Reasoning shows notably better performance in the majority of benchmarks.
Arena Performance
Human preference votes
Model Size
Parameter count comparison
Llama 3.1 405B Instruct has 391.0B more parameters than Phi 4 Reasoning, making it 2792.9% larger.
Context Window
Maximum input and output token capacity
Only Llama 3.1 405B Instruct specifies input context (128,000 tokens). Only Llama 3.1 405B Instruct specifies output context (128,000 tokens).
License
Usage and distribution terms
Llama 3.1 405B Instruct is licensed under Llama 3.1 Community License, while Phi 4 Reasoning uses MIT.
License differences may affect how you can use these models in commercial or open-source projects.
Llama 3.1 Community License
Open weights
MIT
Open weights
Release Timeline
When each model was launched
Llama 3.1 405B Instruct was released on 2024-07-23, while Phi 4 Reasoning was released on 2025-04-30.
Phi 4 Reasoning is 9 months newer than Llama 3.1 405B Instruct.
Jul 23, 2024
2.0 years ago
Apr 30, 2025
1.3 years ago
9mo newerKnowledge Cutoff
When training data ends
Phi 4 Reasoning has a documented knowledge cutoff of 2025-03-01, while Llama 3.1 405B Instruct's cutoff date is not specified.
We can confirm Phi 4 Reasoning's training data extends to 2025-03-01, but cannot make a direct comparison without Llama 3.1 405B Instruct's cutoff date.
—
Mar 2025
Outputs Comparison
Key Takeaways
Phi 4 Reasoning
View detailsMicrosoft
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against Llama 3.1 405B Instruct and Phi 4 Reasoning side-by-side, then vote on the output you prefer.
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FAQ
Common questions about Llama 3.1 405B Instruct vs Phi 4 Reasoning.