Approx 90% of wig wearers have average fitting wigs. This is approx. 22.5 inches around the hairline or where the hairline should be.
As so few people need a petite or a large wig, there is not such a big range to choose from, but manufacturers ARE getting better and more are becoming available all the time.
To be sure about size, measure your head using a soft tape measure. Measure around the head, where the hair line is or should be, above the ears and to the front of the forehead (as shown in diagram).
21" - 21.5 Petite Fitting
22.5" Average Fitting
23" Large Fitting
All wigs are adjustable and have elastic or velcro tabs inside the back of the wig at the hairline to enable you to adjust the wig to suit.