The fastest way to combine PDFs on Mac

The built-in Preview app on your Mac can merge PDFs without installing anything new. Open Preview, go to File > Open, select your first PDF, then drag additional PDFs into the sidebar on the left. Arrange them in the order you want, then go to File > Export As and save as a single PDF. This works for most everyday merging tasks and takes about two minutes.

If you work with PDFs regularly or need more control over how pages combine, third-party tools like PDFtk, Automator workflows, or dedicated PDF apps offer more options. The choice depends on how often you merge files and whether you need features like removing pages, rotating them, or adding watermarks at the same time.

Key Takeaways

  • Preview, which comes with every Mac, can merge PDFs by opening one file and dragging others into its sidebar, then exporting as a new PDF.
  • Automator lets you create a reusable workflow that merges PDFs with one click, useful if you combine files the same way repeatedly.
  • Command-line tools like PDFtk work if you merge many files at once or want to automate the process across multiple folders.
  • Paid apps like PDFpen or Adobe Acrobat add features like page reordering, compression, and batch processing, but cost money monthly or as a one-time purchase.

Using Preview to merge two or more PDFs

Preview is the simplest route for occasional merging. Open Preview from Applications > Utilities, then go to File > Open and select your first PDF. The document appears in the main window with a sidebar on the left showing thumbnails of each page.

Click the sidebar button (it looks like two rectangles) in the toolbar if the sidebar is not visible. Then go to File > Open again and select your second PDF. Instead of replacing the first one, hold down Shift and click to add it to the sidebar. Repeat for as many PDFs as you need. Drag the thumbnails in the sidebar to reorder pages from different files however you want.

Once the pages are in the right order, go to File > Export As. Choose a location, name the new file, and make sure the format is set to PDF. Click Save. Your merged file is ready to use. This method works well for up to 10 or 15 files; beyond that, the sidebar becomes harder to manage.

Creating a reusable Automator workflow

If you merge the same set of PDFs regularly—say, a cover page plus three standard reports every month—Automator can do it in one click. Open Automator from Applications > Utilities, create a new document, and choose Workflow as the type.

In the search box on the left, type "combine" and drag the "Combine PDF Pages" action into the workflow area. A dialog appears asking you to select the PDFs to combine. Click Add File and choose your PDFs in the order you want them. Then add another action by searching for "ask" and selecting "Ask for Finder Items" if you want to choose files each time, or leave it as is if the files are always the same.

Add one more action: search for "save" and drag "Save File As" into the workflow. Choose where to save the merged PDF. Go to File > Save, give your workflow a name like "Merge Monthly Reports", and choose File Format as process. Now you can run this workflow by double-clicking it or dragging files onto it in Finder.

Using command-line tools for batch merging

If you need to merge dozens of PDFs at once or combine files from multiple folders automatically, command-line tools are faster than clicking through a GUI. PDFtk is the most common choice. Install it using Homebrew (a package manager for Mac) by opening Terminal and typing brew install pdftk-java.

Once installed, you can merge PDFs from Terminal with a single command. For example, to combine file1.pdf, file2.pdf, and file3.pdf into merged.pdf, type: pdftk file1.pdf file2.pdf file3.pdf cat output merged.pdf. The word "cat" tells PDFtk to concatenate (join) the files. You can also use wildcards to merge all PDFs in a folder: pdftk *.pdf cat output merged.pdf.

This approach requires some comfort with Terminal, but it is much faster if you do this task often. You can also write a script that runs the same merge command on a schedule or whenever new files appear in a folder.

Paid apps with advanced merging features

If you need to edit PDFs while merging—removing blank pages, rotating pages, adding page numbers, or compressing file size—paid apps offer these features built in. PDFpen costs around $50 as a one-time purchase and lets you drag pages between documents, delete pages, and reorder them visually. Adobe Acrobat Pro costs $15 per month and includes merging, splitting, compressing, and batch processing across many files at once.

Preview and Automator handle basic merging for free, so only move to a paid app if you regularly need features beyond combining files. Many people find that Preview covers 90 percent of their needs and never need to pay.

Choosing between these methods

Use Preview if you merge PDFs fewer than once a week and the files are already in the order you want. It is fast, free, and requires no setup. Use Automator if you merge the same PDFs in the same order repeatedly—it saves time after the first setup. Use command-line tools if you merge many files at once or want to automate the process across folders. Use a paid app only if you need to edit pages while merging or process hundreds of files regularly.

Most Mac users start with Preview and never need anything else. The built-in tool is reliable, straightforward, and does the job without learning new software.

Frequently Asked Questions

Can I merge PDFs that are different sizes or have different page orientations?

Yes. Preview, Automator, and PDFtk all combine PDFs regardless of size or orientation. The pages stay exactly as they were in the original files—a landscape page stays landscape, a small page stays small. If you need to resize or rotate pages to match, you would need to edit each PDF separately first or use a paid app like PDFpen.

What if I want to merge only certain pages from each PDF, not the whole file?

Preview does not let you select individual pages before merging. You would need to delete unwanted pages from each PDF first (Preview can do this—right-click a page in the sidebar and choose Delete), then merge. Automator and paid apps like PDFpen let you pick specific pages more easily.

Does merging PDFs reduce file size or quality?

Merging itself does not compress files or reduce quality. The merged PDF is roughly the same size as all the original files added together. If file size matters, you can compress the merged PDF afterward using Preview (File > Export As, then adjust the Quartz Filter dropdown) or a dedicated compression tool.

Can I merge PDFs on an older Mac?

Preview works on any Mac running OS X 10.7 or later, so nearly all Macs in use today can merge PDFs. Automator is also built in to all modern Macs. PDFtk requires Homebrew, which works on Intel and Apple Silicon Macs running OS X 10.5 or later. Older Macs may have trouble with newer versions of these tools.

Is it safe to merge PDFs that contain sensitive information?

Merging itself does not change the security of a PDF. If a PDF is password-protected, Preview will ask for the password before opening it. If you merge password-protected PDFs, the resulting file is not automatically protected—you would need to add password protection afterward using Preview (File > Export As, then Options) or a paid app.