It’s very important to have the correct size of wig for a comfortable fit. Too tight and it will be very uncomfortable at the end of the day. It’s better if it’s slighter bigger as it can be adjusted to fit tighter.
You want to position the measuring tape around your head (as seen in diagram) where the hairline of the wig will sit.
If you have hair, you may want to add extra to your measurement, depending on how much hair you have. Please get in touch if you are unsure.