The fastest way to merge two PDFs depends on what you have on your computer

If you're using Windows 10 or 11, you can merge PDFs without installing anything new — Microsoft Edge has a built-in PDF tool that lets you combine files. On Mac, Preview does the same thing. If you're on an older Windows version or prefer a dedicated tool, free programs like PDFtk or Smallpdf's desktop version work on any system. The steps differ slightly depending on which method you choose, but all of them take under five minutes.

The method you pick matters most if you're doing this regularly or if you need to merge more than two files at once. One-time merges are easiest with what you already have. Repeated merges are faster with a dedicated tool because you'll remember the steps.

Key Takeaways

  • Windows 10 and 11 users can merge PDFs directly in Microsoft Edge without downloading anything.
  • Mac users can drag and drop PDFs into Preview to combine them in seconds.
  • Free desktop programs like PDFtk work on Windows, Mac, and Linux if you prefer a dedicated tool.
  • Online tools like Smallpdf or ILovePDF work in any browser but require uploading your files to their servers.
  • The order of your pages matters — most tools let you rearrange before merging.

Merging PDFs in Microsoft Edge on Windows

Open both PDF files in Microsoft Edge (the browser that comes with Windows). You can do this by dragging each file into an Edge window or by right-clicking the file and selecting "Open with" and choosing Edge.

Once the first PDF is open in Edge, look for the three-dot menu in the top right corner. Click it, then select "Print" (or press Ctrl+P). In the print dialog, change the printer dropdown from your normal printer to "Print to PDF" or "Microsoft Print to PDF". Click the "More settings" or "Additional settings" link to expand the options.

In the expanded menu, you'll see a field labeled "Pages" or "Print range". Leave it blank to print all pages of the first PDF. Click "Save", choose where to save the file, and give it a temporary name like "merged_temp.pdf". This creates a copy of your first PDF.

Now open the second PDF in a new Edge tab. Repeat the print-to-PDF process, but this time you're going to use a different approach: instead of saving a new file, you'll append to the one you just created. Unfortunately, Edge's print dialog doesn't have a built-in append option, so this method works best if you use a dedicated tool for the second step. Skip to the PDFtk section below if you want to avoid this extra step.

Merging PDFs in Preview on Mac

Open the first PDF in Preview (the app that comes with macOS). Then open the second PDF in a new Preview window — go to File > Open and select the second file, or drag it into the Dock's Preview icon while holding the Option key.

In the first Preview window, go to View menu and select "Thumbnails" if it's not already showing. You'll see a sidebar on the left with small images of each page. Now switch to the second Preview window, select all its pages (Cmd+A), and copy them (Cmd+C).

Go back to the first Preview window and click at the end of the thumbnail list — after the last page. Paste the pages (Cmd+V). The second PDF's pages will appear at the end. If you want them in a different order, drag the thumbnails around. When you're done, go to File > Export As, choose a location and filename, and save.

Using PDFtk on Windows, Mac, or Linux

PDFtk is a free command-line tool that works on all operating systems. Download it from pdftk.com and install it like any other program. You don't need to open an interface — you'll use the command line (Terminal on Mac, Command Prompt on Windows).

Open your command line and navigate to the folder where your PDFs are stored. On Windows, type cd C:\Users\YourName\Documents (replace "YourName" with your actual username). On Mac, type cd ~/Documents. Then type this command, replacing "file1.pdf" and "file2.pdf" with your actual filenames:

pdftk file1.pdf file2.pdf cat output merged.pdf

Press Enter. PDFtk will create a new file called "merged.pdf" in the same folder, containing both files in order. If you want the pages in a different order, swap the filenames. If you want to merge more than two files, add them to the command: pdftk file1.pdf file2.pdf file3.pdf cat output merged.pdf

Using an online tool like Smallpdf or ILovePDF

Go to smallpdf.com or ilovepdf.com in your browser. Both sites have a "Merge PDF" option on their homepage. Click it.

You'll see a button to upload files. Click it and select your first PDF, then click again to add your second PDF. Both tools let you drag and drop files instead if you prefer. Once both files are uploaded, you'll see thumbnails of each page. Drag them to reorder if needed.

Click the "Merge" or "Combine" button. The tool will process your files and give you a download link. Click it to save the merged PDF to your computer. The file will be deleted from the website's servers after a few hours, but you should download it right away.

The downside of online tools is that your PDFs are uploaded to someone else's server. If your files contain sensitive information, use one of the offline methods instead (Edge, Preview, or PDFtk).

Rearranging pages before you merge

Most tools show you thumbnails of each page before merging, which lets you change the order. In Preview and online tools, drag the thumbnails to reorder. In PDFtk, you control the order by the order you list the filenames in the command.

If you only want certain pages from each file, most online tools let you delete unwanted pages before merging. PDFtk can do this too, but it requires a more complex command — for example, pdftk file1.pdf cat 1-5 file2.pdf cat 3-8 output merged.pdf would take pages 1 through 5 from file1 and pages 3 through 8 from file2. Edge and Preview don't have built-in page deletion, so you'd need to edit the PDFs separately first.

What to do if the merged file looks wrong

If pages are in the wrong order, you uploaded them in the wrong order. Delete the merged file and try again, making sure you add the files in the sequence you want.

If the file is much larger than you expected, the PDFs may contain high-resolution images. This is normal and doesn't mean anything went wrong. If file size matters (for example, if you're emailing it), you can compress the merged PDF using the same online tools — most have a "Compress PDF" option.

If the merged file won't open or looks corrupted, try a different method. Sometimes a PDF that's damaged or encrypted will merge fine in one tool but not another. PDFtk and Preview are usually the most reliable for problem files.

Frequently Asked Questions

Can I merge more than two PDFs at once?

Yes. In Preview, open all the PDFs and copy pages from each one into the first file. Online tools usually let you upload as many files as you want. PDFtk can merge any number of files — just list them all in the command separated by spaces.

Will merging PDFs make the file bigger?

The merged file will be roughly the size of both original files added together. If you're merging a 5 MB file and a 3 MB file, expect about 8 MB. Compression during merging is minimal unless you use an online tool's compress feature afterward.

Can I merge PDFs that have different page sizes?

Yes. All methods handle different page sizes without problems. A merged PDF can contain pages that are 8.5 by 11 inches, 11 by 17 inches, or any other size in the same document.

Do I need to install software to merge PDFs?

Not if you use Edge, Preview, or an online tool. PDFtk requires installation, but it's free and takes a minute. If you merge PDFs often, installing PDFtk saves time because you won't have to open a browser or navigate menus each time.

What happens to my original files after merging?

They stay on your computer unchanged. All these methods create a new merged file without touching the originals. You can delete the originals once you've confirmed the merged file looks correct.