• The Priority Mail Flat Rate Box is $7.70 for any U.S. destination.
• The inside dimensions for the two boxes available are 11" x 8.5" x 5.5" and 13.625" x 11.875" x 3.375".
• The contents of the flat rate box must be neatly contained inside of the box with adhesive packaging tape.
• The box must close securely and retain its shape when taped with adhesive.
• The shape of the box may not be changed or enlarged to fit its contents.
Extra services such as Delivery Confirmation™, Signature Confirmation®, and Insurance are available to use with Priority Mail Flat-Rate Envelopes and Boxes. Note: Priority Mail Flat Rate Envelopes and Boxes can hold a maximum of 70 lbs.