The USPS has several requirements for postcard setup. While the front of a postcard can contain any image or design, the back needs to have space for postage, postal markings and a properly written address. These guidelines apply to standard postcards, which are 6 inches wide and 4.25 inches tall.Continue Reading
The postage clear zone is the space where a stamp or printed postage mark will go. No other marks can be in this area, which is a square with 1.25 inches per side in the top right corner of the postcard.
The mailing address must go on the right side of the postcard. Write or print the complete address within 2.75 inches of the right edge of the card and within 2.75 inches of the bottom edge. Leave a blank space at least 0.63 inches tall at the bottom of the card for bar codes and postal markings.
Make sure that the postage zone and mailing address are in the proper spaces on the back of the postcard. The space outside of the postage and address areas can contain the text or images you desire, but they cannot contain postage marks or the address. If these are not in the designated areas, the postcard will not be delivered.