If you don't need the white borders around the content of a PDF, remove them in Adobe Acrobat XI by using the Crop tool. Don't worry -- you don't have to manually crop each page in a 200-page document; Acrobat offers a handy option to automatically remove white margins from all pages at once. If, however, your PDF contains scanned images, Acrobat will be unable to crop them because they don't contain the pixel-free margins of regular distilled PDFs that come from programs such as Microsoft Word or Adobe InDesign. If this is the case, manually crop the scans.
Removing Unnecessary Borders
Press "Ctrl-O," select the PDF you want to edit and then click the "Open" button to open the document in Adobe Acrobat XI. Locating the Removing White Margins option is not as straightforward as it sounds because the option is not present in any of the menus.
Click the "Tools" button in the upper right corner of the window and then click the "Pages" node to expand it. Click the "Crop" option in the Manipulate Pages section to select the tool. The cursor changes to a crosshair.
Double-click anywhere in the document to display the Set Page Boxes window. From this window, you can control the margins of the PDF, as well as remove the white margins.
Check the "Remove White Margins" box in the Margin Controls section and then click the "All" radio button in the Page Range section to crop all pages in the PDF. The Remove White Margins option is available only when the "CropBox" option is selected from the "Apply to" drop-down box in the Margin Controls section.
Click "OK" to crop the pages of the PDF and remove the white margins. Scroll through the document to ensure the margins are cropped correctly and then save the changes by pressing "Ctrl-S." To save the cropped PDF in a different location, click "File" and choose "Save As" from the menu or press "Shift-Ctrl-S."
If the PDF contains scanned images, you must crop the white margins manually. Select the "Crop" tool and then draw a rectangle with your mouse around the content you wish to preserve. Use the corner handles of the rectangle to adjust its size. Double-click inside the rectangle and then click "OK" to crop the page.
To crop only specific pages, click the "From" radio button in the Page Range section and then choose the start page and end page. You can also choose to crop only odd pages or even pages by selecting the "Odd Pages" or "Even Pages" option from the "Apply to" drop-down box in the Page Range section.
To restore the margins, select the "Crop" tool, double-click anywhere in the PDF and then click the Set To Zero button in the Margin Controls section. Click "OK." The Set To Zero button is disabled if the Remove White Margins box is checked.
You can change the size of your pages using the controls in the Change Page Size section. You can choose one of the standard page sizes from the "Page Sizes" drop-down box or use a custom page size by clicking the "Custom" radio button.
You can undo the changes by pressing "Ctrl-Z."
Removing the white borders creates pages of different widths in most cases. To avoid this, check the "Constrain Proportions" box in the Set Page Boxes window. Note that some pages keep at least part of their borders if this option is enabled.
Cropping the PDF does not reduce its file size because the white borders are hidden, not removed.