The sizes of USPS flat rate boxes are as follows: – Small Flat Rate Box: 8 11/16″ x 5 7/16″ x 1 3/4″– Medium Flat Rate Box: 11 1/4″ x 8 3/4″ x 6″– Large Flat Rate Box: 12 1/4″ x 12 1/4″ x 6″– Large Flat Rate Board Game Box: 23 11/16″ x 11… Continue reading what are the sizes of usps flat rate boxes?
