Choose a hat based on your body shape. Taller individuals should opt for larger hats rather than smaller ones, as smaller hats can give an impression of top-heavy. Conversely, shorter individuals should choose smaller hats. Tall women should avoid tall-top hats, as they can make them seem even taller. Short women should steer clear of wide-brimmed flat-top hats, as they can make them appear shorter. Just like wearing clothes, hats should accentuate your strengths and conceal your weaknesses. Even if you're satisfied with the hat, it should also look pleasing to others. The style and color of the hat must match with your clothes, scarves, gloves, and shoes. Ladies who wear glasses should avoid hats with intricate decorations on top, as they should not cover the forehead. Choose a hat that is higher to showcase your casual elegance and refined demeanor.

The size of men's hats, indicated by the number, refers to the circumference in centimeters, making the selection process quite convenient. However, since some hats shrink after washing, it's advisable to choose a slightly larger size. Generally, adult men's hat sizes range from 55-56, children's hats from 50-55, and baby hats from 42-46. Women's adult hats, sun hats, and sport hats are only categorized into three sizes: 1-3. Knitted hats do not have specific sizes, as they can stretch to accommodate; some are even measured by weight in grams.