Microsoft Phi-4 — Textbook-Quality Training, Frontier Math Performance, and the Best Small Reasoning Models of 2025

Microsoft's Phi-4 family (December 2024–April 2025) proves that data quality beats parameter count. A 14B model that rivals 70B competitors on math and reasoning, a 3.8B mini with 128K context, and reasoning variants trained on o3-mini-generated traces. MIT license. We review the full lineup.