Please keep in mind that head sizes vary widely among all ages, but especially among babies and children. The age ranges on this size chart are suggestions based on averages. For the best fit, measure your child's head circumference. If your child's measurement or age is borderline, order the bigger size. A slightly too big hat looks better than a slightly too small hat.
Extra Small: 0-3 months, head circumference 14-16 inches (35-40 cm)
Small: 3-12 months, head circumference 16-18 inches (40 to 45 cm)
Medium: 12 months-3T, head circumference 18-20 inches (45 to 50 cm)
Large: 3T and up, head circumference 20-22 inches (50 to 55 cm)