Depending on your printer’s capabilities, you can create and print all kinds of document sizes in Word. For example, you can type up an address and return address in Word to print on an envelope, or you can print legal size pages, and so on.
Click the Page Layout tab.
Click the Size button.
Click a paper size.
Word applies the new size to the page.
Tip
Dialog Box Option You can also change paper sizes through the Page Setup dialog box. At the bottom of the Size drop-down menu, click More Paper Sizes. The Page Setup dialog box opens to the Paper tab options, including options for selecting a paper source for your printer.