Women's shoe sizes vary by region, with the most common systems being the US, UK, and EU sizes. In the US, women's sizes typically range from 5 to 12, with half sizes available. The UK system usually runs one size smaller than the US, while the EU sizes are based on the length of the foot in centimeters. To find the right size, it's essential to measure both feet, as they can differ in size. Shoe sizes can also vary between brands and styles, so trying on shoes or checking specific size charts is recommended for the best fit.