We had earlier covered about the steps required for changing the paper size in Word. And to this couple of readers had asked question on How to add A5 to the paper size list. So in case you don’t see A5 or any other paper size then use the custom paper size option available as Page Setup. Let us see how to add A5 paper size to the Page Setup in Word 2016, 2013 & 2010
Click File then Print menu and navigate to Settings section.
Click the drop down with value displayed as Letter. Then select the More Paper Sizes from the list.
In the Page Setup window, navigate to Page Size and set the value for the drop down to Custom Size. Then enter the Width and Height for A5 Paper Size as 5.8” and 8.3” respectively. Then click the OK button to confirm and save the changes.
Note :- If you are not sure about the Height and Width of Paper Sizes (4A0 to A10) then refer this website.