Standard postcard dimensions acceptable for mailing through the United States Postal Service are generally within a rectangular shape of at least 3-1/2 inches high by 5 inches long and no more than... Read more »
Postal regulations govern the physical dimensions, addressing conventions, and postage necessary for postcards mailed within the United States. For example, a standard postcard must be rectangular, at least 3.5 inches high and... Read more »
