How to Combine and Merge PDF Files Using Preview in macOS

If you need to merge two separate PDF documents into a single file—such as combining a signed cover letter with a multipage resume—you do not need to buy an Adobe Acrobat subscription. Apple has built powerful PDF manipulation tools directly into the native macOS Preview application, allowing you to combine documents seamlessly using a simple drag-and-drop interface.

How to Combine Two PDFs

The secret to merging documents in Preview relies entirely on utilizing the sidebar thumbnail view.

1. Locate the two PDF files on your Mac (e.g., Document_A.pdf and Document_B.pdf).
2. Double-click Document_A.pdf to open it in the Preview app.
3. Look at the top toolbar and click the View Menu button (it looks like a small window with a sidebar).
4. Select Thumbnails from the drop-down menu. A sidebar will appear on the left side of the window showing a small preview of every page in Document A.
5. Now, locate Document_B.pdf in your Finder window.
6. Click and drag the icon for Document_B.pdf directly from the Finder and hover it over the Preview thumbnail sidebar.

This next step is critical: as you hover the file over the sidebar, look closely at the blue highlight line that appears. If you drop the file on top of an existing thumbnail, it might replace it. You must ensure the blue line appears exactly where you want the new document to begin (usually at the very bottom of the thumbnail list). Once the line is positioned correctly, release the mouse button.

Preview will instantly import every page from Document B and append it to Document A.

How to Merge Specific Pages

If you do not want to merge the entirety of Document B, but rather just a single specific page, the process is slightly different.

1. Open both Document_A.pdf and Document_B.pdf in two separate Preview windows.
2. Ensure the Thumbnails sidebar is open and visible in both windows.
3. Position the two windows side-by-side on your screen.
4. In the Document B window, locate the specific page thumbnail you want to extract.
5. Click and drag that single thumbnail directly into the thumbnail sidebar of the Document A window.

The page will be instantly copied over. You can also hold down the Command key while clicking to select multiple specific thumbnails, or hold down the Shift key to select a continuous block of pages before dragging them over.

Finalizing the Document

Once you have dragged all your pages together, you can click and drag the thumbnails up and down in the sidebar to perfectly reorder the pagination. When you are satisfied, press Command + S to save the file. The two documents are now permanently merged into a single PDF.