Measuring tips to ensure the best fit of your hat Head circumference. XS – 20,5-21" / 52-53 cm (non-returnable size) S – 21,2-21,7" / 54-55 cm M – 22-22,5" / 56-57 cm L – 22,8-23,3" / 58-59 cm XL – 23,6-24" / 60-61 cm If you need a custom fit, please provide your head circumference in the "notes" section of your order and we will check the size for you. Attention - XS and CUSTOM SIZES are not refundable.