The fastest way: drag files into Preview

The simplest method on Mac is to use Preview, the built-in app that opens PDFs by default. Open the first PDF in Preview, then drag the second PDF's icon directly into Preview's sidebar on the left. Preview will add all pages from the second file to the first one in the order you drop them. When you're done, go to File > Export As, choose PDF as the format, and save.

This method keeps both files on your computer — nothing leaves your Mac. It works for any number of PDFs, though dragging more than three or four at once can get confusing. The sidebar shows you exactly where each page will land, so you can reorder them before saving if you need to.

Key Takeaways

  • Preview, which comes free with every Mac, can merge PDFs by dragging files into its sidebar and exporting the result as a new PDF.
  • If you need to reorder pages or delete some before merging, Preview's thumbnail view lets you do that without opening a second program.
  • Automator, also built into Mac, can merge the same two PDFs every time you run it, which saves time if you do this regularly.
  • Online PDF tools require you to upload files to someone else's server, so using Preview or Automator keeps your documents private by default.

Reordering or removing pages before you merge

If the second PDF's pages need to go in the middle of the first one, or if you want to skip some pages entirely, Preview's sidebar is where you control that. Open the first PDF, then drag the second PDF into the sidebar. You'll see thumbnails of every page from both files.

Click and drag any thumbnail to move it to a different spot. Right-click a page and select Delete to remove it. Once the pages are in the order you want, export as PDF. This approach is faster than opening a separate tool — you see the whole merged document before you save it.

Using Automator to merge the same PDFs repeatedly

If you merge the same two PDFs on a regular schedule — say, monthly reports or recurring invoices — Automator can do it automatically. Open Automator (in Applications > Utilities), create a new Quick Action, and search for "Combine PDF Pages" in the action library on the right.

Drag that action into your workflow. Set it to ask you which PDFs to combine each time you run it, or point it to specific files in a folder. Save the action with a name like "Merge Monthly Reports." After that, you can run it from Finder by right-clicking a PDF and selecting your action from the Quick Actions menu.

This saves time if you're doing the same merge weekly or monthly, but it takes a few minutes to set up the first time. If you only merge PDFs once in a while, Preview's drag-and-drop method is faster.

Why not to use online PDF tools for sensitive documents

Many websites offer free PDF merging — you upload both files, they combine them, and you read the result. The trade-off is that your PDFs go to someone else's server. Even if the site promises to delete files after an hour, you have no way to verify that, and you're trusting the site's security practices with whatever is in those documents.

If your PDFs contain financial information, medical details, or anything you wouldn't want to share, Preview and Automator are better choices because the files never leave your Mac. If your PDFs are public documents or test files, an online tool is fine — just know what you're trading.

What to do if Preview won't open one of your PDFs

Occasionally a PDF is corrupted or uses an older format that Preview struggles with. Try opening it in Adobe Acrobat Reader (free, available from Adobe's website) instead. If Acrobat Reader opens it, you can export it as a new PDF from there, which often fixes the corruption. Then try merging it in Preview.

If neither Preview nor Acrobat Reader will open the file, the PDF itself may be damaged beyond repair. In that case, you may need to recreate it from the original source — the Word document, email, or website it came from.

Keeping your merged PDF organized

When you export your merged PDF, give it a name that tells you what's inside and when you made it. Instead of "Merged PDF," try "2024 Tax Documents Combined" or "Invoice Jan-Mar 2024." This makes it easier to find later and tells you at a glance whether you're looking at the right file.

If you merge PDFs regularly, create a folder called "Merged Documents" or "Combined Reports" and save them all there. This keeps them separate from your original files, so you always know which version is the final one.

Frequently Asked Questions

Can I merge more than two PDFs at once?

Yes. In Preview, drag as many PDFs as you need into the sidebar. Automator can also combine three, four, or more PDFs in a single action. The process is the same — just add each file to the sidebar or workflow in the order you want them.

Will merging PDFs change the quality or size of the files?

Preview preserves the original quality of each page. The merged file's size is roughly the sum of the two original files, though it may be slightly smaller because Preview compresses them a little during export. You can control compression by choosing different export settings in Preview's save dialog.

What if I want to keep the original files separate?

Always use File > Export As instead of File > Save. Export As creates a new file and leaves your originals untouched. If you use Save, you'll overwrite the first PDF with the merged version.

Can I merge PDFs on an older Mac?

Preview and Automator come with every version of macOS, so yes. The steps are the same on older Macs as they are on current ones. If you're running macOS 10.12 or later, you have everything you need.

Is there a way to merge PDFs without using Preview?

Yes — Automator, Adobe Acrobat Pro, or command-line tools like ImageMagick. For most people, Preview is the simplest option because it's already on your Mac and requires no setup. Automator is worth learning if you merge PDFs regularly.