Sizes for Postcards. Postcards are an inexpensive way to get an immediate
message to customers. Whe. All measurements are in inches. These are standard postcard sizes. Check with
United States Post Of. Learn about the different Postcard sizes & choose the best option for your printing
& desig. Postcard USPS postal requirements & specifications for automated mailing
discounts with downloa. May 14, 2014 . What do you mean the post office won't let me mail it this way?. Postcard si. This updated postal guide follows current USPS regulations for all our mailing
sizes and formats. W. This is the most common size of postcard we print and mail. This is often also
referred to as a 4 x. In the end, the best size of postcard will come down to your marketing goals,
target. If you wan.