Maximize your protection in style with Certified UPF 50+ headwear. UPF stands for Ultraviolet Protection Factor and is a rating system to indicate the UV (Ultraviolet) protection provided by fabrics. UPF measures how much of the sun’s UV radiation is absorbed or “blocked” by fabric, effectively protecting the skin underneath. UPF ratings range from 15 to 50, and a higher UPF rating indicates greater protection. Hat Habit has you covered.