Phi-3.5-mini-instruct vs Phi 4 Reasoning
Phi 4 Reasoning significantly outperforms across most benchmarks.
Microsoft · Microsoft · Updated for 2026
Which is better?
Phi-3.5-mini-instruct outperforms in 0 benchmarks, while Phi 4 Reasoning is better at 3 benchmarks (Arena Hard, GPQA, MMLU-Pro). Phi 4 Reasoning significantly outperforms across most benchmarks.
Based on current benchmark, pricing, and model metadata for 2026.
Choose Phi-3.5-mini-instruct
- you want predictable pricing at $0.10/M input and $0.10/M output
Choose Phi 4 Reasoning
- you want the strongest raw capability — it leads on 3 of 3 shared benchmarks
- you want the most recent training data — it shipped Apr 2025
At a glance
The differences that matter most.
Performance Benchmarks
Comparative analysis across standard metrics
Phi-3.5-mini-instruct outperforms in 0 benchmarks, while Phi 4 Reasoning is better at 3 benchmarks (Arena Hard, GPQA, MMLU-Pro).
Phi 4 Reasoning significantly outperforms across most benchmarks.
Arena Performance
Playground indexes and blind preference scores
Model Size
Parameter count comparison
Phi 4 Reasoning has 10.2B more parameters than Phi-3.5-mini-instruct, making it 268.4% larger.
Context Window
Maximum input and output token capacity
Only Phi-3.5-mini-instruct specifies input context (128,000 tokens). Only Phi-3.5-mini-instruct specifies output context (128,000 tokens).
License
Usage and distribution terms
Both models are licensed under MIT.
Both models share the same licensing terms, providing consistent usage rights.
MIT
Open weights
MIT
Open weights
Release Timeline
When each model was launched
Phi-3.5-mini-instruct was released on 2024-08-23, while Phi 4 Reasoning was released on 2025-04-30.
Phi 4 Reasoning is 8 months newer than Phi-3.5-mini-instruct.
Aug 23, 2024
2.0 years ago
Apr 30, 2025
1.3 years ago
8mo newerKnowledge Cutoff
When training data ends
Phi 4 Reasoning has a documented knowledge cutoff of 2025-03-01, while Phi-3.5-mini-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 Phi-3.5-mini-instruct's cutoff date.
—
Mar 2025
Outputs Comparison
Judge for yourself.
Run your own prompts against Phi-3.5-mini-instruct and Phi 4 Reasoning side-by-side, then vote on the output you prefer.
FAQ
Common questions about Phi-3.5-mini-instruct vs Phi 4 Reasoning.