What size boxes are available for USPS flat rate shipping?

USPS flat rate shipping boxes come in 5 sizes. The smallest flat rate box is 8 11/16" x 5 7/16" x 1 3/4". There are 2 medium flat boxes of different dimensions: 11 1/4" x 8 3/4" x 6" and 14" x 12" x 3 1/2". The large flat rate box is 12 1/4" x 12 1/4" x 6" in size. There is also a board game box available that is 24 1/16" x 11 7/8" x3".