As of now all of our shipping is done with USPS flat rate boxes.
A small flat rate box measures 8 11/16" x 5 7/16" x 1 3/4" and can fit around 8 Performance foundations and costs $8. A medium box measures 11 1/4" x 8 3/4" x 6" or 14" x 12" x 3 1/2" and can hold about 2 wigs and costs $13.50.
If the website algorithm charges you for a medium, but we manage to fit your order in a small, will will refund you the shipping difference. If you want to know if specific items will fit in a small box, please email us. Or if you are wanting us to ship outside of the U.S. please email us. Hopefully this helps you with your shopping experience.