In Excel's Page Setup, the 11" X 17" paper size is called "Tabloid". Here's how you can set it up:

1. Open the Excel file you want to print on 11" X 17" paper size.
2. Click on the "Page Layout" tab in the ribbon.
3. Click on the "Size" button in the "Page Setup" group.
4. Select "Tabloid (11" X 17")" from the drop-down menu.
5. Click "OK" to apply the changes.

Now your Excel file is set up to print on 11" X 17" paper size. You can preview the print layout by clicking on the "Print Preview" button in the "Page Setup" group.