One of the most important factors for a well-fitted wig is the measurements. Here at AyayBella Collection we currently have three wig sizes available, small (21 inches), medium (22 inches), and large (23 inches). XS(20 inches) and XL (24 inches) will be available soon. In order to get the correct size for our Ready to Ship wigs, you will use the circumference measurement. When ordering a customized wig all measurements are required (this service is coming soon).