Phi-4 is the newest member of Microsoft's Phi series of small language models, featuring 14 billion parameters and excelling in fields requiring complex reasoning, such as mathematics. Phi-4 achieves a balance between size and quality by leveraging high-quality synthetic datasets, carefully curated organic data, and innovations in post-training. It represents a technological advancement in small language models (SLMs) by Microsoft, pushing the boundaries of AI capabilities. Phi-4 is available on Azure AI Foundry and will launch on the Hugging Face platform in the coming weeks.