By default, the iWork Pages for iPad app formats documents for standard letter size paper. They are designed to be printed on 8 ½ x 11 paper. But, you don't have to have to stick with this paper size. You can opt to format your document for A4 paper size.
To change the paper size for documents you create in iWork Pages for the iPad, just follow these simple steps:
1. Open your document in iWork Pages
2. Tap the Tools icon in the upper right side of the window
3. Select Document Setup in the popup menu
4. Tap the bottom right side of the document in the Document Setup screen
5. Select A4
6. Tap Done