All Myssy hats should feel a little tight in the beginning, the hat adjusts to the size and shape of your head within the first week of use.
Our One Size / M fits 85% of our customers. It fits well for hat sizes between 54 to 59 cm. Each Myssy is unique, and though all our grannies work off from the same size chart, not all hats are precisely the same.
If you are unsure of the size or you know you will need a larger size, you can always leave a comment while sending your order in and let us know you would like to have a bigger variation. We will do our best to take this into account!