The size of A4 paper is 8.27 inches wide by 11.69 inches tall, or 210 millimeters wide by 297 millimeters tall. A4 paper is commonly used in Europe and is roughly comparable, although narrower and longer, to the U.S. paper size of 8.5 inches wide by 11 inches tall.
A4 paper works in most printers, even these in the United States. It is frequently used for newsletters, documents and magazines. Reducing an A4 page by 94 percent enables a photocopy of the page to fit on standard-sized U.S. paper. Reducing standard-sized U.S. paper by 97 percent makes it fit an A4-sized photocopy.