Measuring Your Head Size
Every head has its own unique size and shape, which can be measured with a flexible tape measure or even a piece of string.
Take the tape measure and encircle your head, just above the top of your ears. Make sure that the tape measure goes over that small bump at the back of your head. Please don't pull it tightly. Leave a little 'ease' so that one finger can fit under the tape. An ear-to-ear measure can be helpful too.
Measure three times: it is surprising how it can vary!
Inches or centimetres are fine.