Take a measuring tape and place it around the circumference above your eyes and ears, surrounding the widest part of the top of your head. Adjust the strap to the position you want the hat to rest in (generally for most people it is about 2cm above the eyebrows and ears). Make sure the tape is attached without overtightening. Perform this process several times to confirm the accuracy of the measurement. If possible, ask someone to help ensure that the tape measure is level and the measurement is accurate. It is important to note that our products are available in different sizes. We recommend that you follow our instructions to determine your size before making your choice from the available options. In addition, we want to remind you that all purchases made within Mexico include the advantage of making a first size change for free. This is designed to give you greater confidence and security when placing your order. Click on this link and watch our video on how you can measure yourself and know your ideal size.