To combine PDF files, open Acrobat and choose Combine files (Menu on Windows, File on Mac), add your files, drag the thumbnails into order and select Combine. On a Mac you can do it free in Preview by dragging page thumbnails from one PDF's sidebar into another's. Duplicate your originals first.
Merging PDFs is one of those jobs that should take a minute and somehow eats half an hour, usually because the file you wanted to add is in the wrong place or the pages came out in the wrong order. There are two reliable routes: Adobe Acrobat on Windows or Mac, and Preview if you're on a Mac. Both are covered below, with the catches that trip people up.
Combine PDF files in Adobe Acrobat
- Open Acrobat. On Windows choose Menu then Combine files. On a Mac choose File then Combine files.
- Select Add Files and pick the documents you want, or drag and drop them straight into the Combine files window.
- Arrange the files and pages. Drag the thumbnails to change the order, hover over a file and select the expand icon to see its individual pages, and remove any page you don't want in the final version.
- Select Combine in the upper-right corner.
- Rename the merged file if you want to, then save it where you'll find it again.
Acrobat doesn't only take PDFs. Adobe says it can merge PDFs, Word, Excel, PowerPoint, audio, video and web files into a single, sequential PDF, and you get a preview of everything before you commit. That's handy when a proposal is a Word document, the numbers are in a spreadsheet and the signed terms are already a PDF. One tidy file goes out instead of three attachments.
Combine PDFs on a Mac with Preview
You don't need Acrobat on a Mac. Preview, the app that opens PDFs by default, can merge them, although it works by dragging pages rather than pressing a Combine button.
- Open each PDF in Preview.
- In each one, choose View then Thumbnails so the page thumbnails show in the sidebar.
- Drag the thumbnails you want from the sidebar of one PDF into the sidebar of the other. Hold Command and click to select thumbnails that aren't next to each other.
- Drop them at the end of the document or between two pages, then drag any thumbnail to reorder.
There's a faster way to add a whole file: drag the PDF's icon from the Finder into the sidebar of the document that's already open. Apple's tip is the one I'd use for anything longer than a few pages.
Which method should you use?
| Acrobat | Preview on Mac | |
|---|---|---|
| Works on | Windows and Mac | Only on a Mac |
| How it combines | Add files, reorder thumbnails, press Combine | Drag page thumbnails between sidebars |
| Accepts Word, Excel, PowerPoint | Yes, merges them into the PDF | PDFs only, so convert other files first |
| Preview before merging | Yes, you can expand each file's pages | Yes, you see the thumbnails as you drag |
| Best for | Mixed file types and big batches | Quick merges of a few PDFs |
The catch with Preview: it saves as you go
Here's the rule people miss. Apple warns that changes you make to a Preview document are saved automatically. If you drag pages from one PDF into another, you've changed the receiving file for good, and there's no Save button to back out of. If you want to keep the original PDFs as well as the combined one, choose File then Duplicate on each before you start. It takes ten seconds and saves you from hunting through backups.
Open files get merged automatically in Acrobat
This one catches people out in the other direction. When you choose Combine files while other documents are open in Acrobat, those open files are included in the merge automatically. Adobe's prompt is to choose Add open files. If you only wanted two of the five documents you have open, close the rest first, or remove the extra files in the Combine files window before you press Combine.
Fixing the order and dropping pages
- Wrong order: drag the thumbnails in the Combine files window until the sequence is right, then merge. It's much quicker than merging and reorganising afterwards.
- A cover page you don't need: expand the file, select the page and remove it before you merge. That keeps your source file untouched.
- One file way too long: expand it and delete the pages you don't need rather than combining everything and cutting later. If you do need to cut pages afterwards, my guide on turning a blog post into a PDF shows how I keep source files tidy.
Before you send the combined file
A merged PDF is often the file that goes to a client, so give it thirty seconds of attention. Scroll through it once from the first page to the last. Check that no page is sideways, that nothing from the wrong document has crept in and that the file name says what it contains. A name like final-merged-v2 tells the person nothing.
If the finished file is too large to email, the next job is shrinking it. The usual culprit is images, not text. And if you send design files as well as documents, my guide to sending an Illustrator file without it arriving broken covers the same email headaches.
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My verdict
If you've got Acrobat, use Combine files: add everything, put it in order in the preview and press Combine. If you're on a Mac and it's a few PDFs, Preview does the job without installing anything, just remember it saves your changes immediately, so duplicate first. Either way, check the page order before you send it.
Frequently asked questions
How do I combine PDF files into one?
In Acrobat, choose Combine files from the Menu (Windows) or File menu (Mac), add your files, arrange the thumbnails and select Combine. On a Mac you can also drag thumbnails between PDFs in Preview.
Can I combine PDF files without Acrobat?
On a Mac, yes. Open the PDFs in Preview, show Thumbnails in the sidebar and drag pages from one document into the other.
Can I merge Word and Excel files into a PDF?
Acrobat can combine PDFs, Word, Excel, PowerPoint, audio, video and web files into a single PDF. Preview only handles PDFs.
Will combining PDFs change my original files?
Preview saves changes automatically, so duplicate the originals first. In Acrobat you merge into a new file that you name and save yourself, so check the file name before you save over anything.
How do I change the page order in a combined PDF?
In the Combine files window in Acrobat, drag the thumbnails into order before you press Combine. In Preview, drag the thumbnails in the sidebar.
