The fastest way depends on what's already on your computer
You can merge PDFs using free software that's likely already installed, or through a web browser without downloading anything. On Windows, the built-in Print to PDF feature works for combining files. On Mac, Preview handles it natively. If you want a dedicated tool, PDFtk (free, command-line) and Ghostscript (free, powerful) both merge PDFs reliably. For a graphical interface without installation, ILovePDF and Smallpdf are browser-based options that work on any device.
The method you choose depends on how many PDFs you're combining, whether you need to reorder pages, and whether you want to keep the files on your computer or use a web tool. Most people find the easiest route is whichever tool they already have open.
Key Takeaways
- Mac users can open all PDFs in Preview, drag them into the sidebar in the order you want, then export as a single file.
- Windows users can print multiple PDFs to a single PDF using the Microsoft Print to PDF driver, though you'll need to do this one file at a time.
- Free desktop software like PDFtk and Ghostscript merge PDFs from the command line and work on Windows, Mac, and Linux.
- Web-based tools like ILovePDF and Smallpdf let you upload PDFs, reorder pages, and download the merged result without installing software.
- If you need to merge PDFs regularly, a dedicated tool saves time; if it's a one-time task, your browser or built-in OS features are usually enough.
Merging PDFs on Mac using Preview
Preview is the simplest method on Mac because it's built in and handles page reordering visually. Open the first PDF in Preview, then go to File > Open and select the other PDFs you want to merge while holding Command. They'll open as separate windows or tabs depending on your settings.
Click the sidebar icon (it looks like two rectangles) in the top left of the Preview window. You'll see thumbnails of all pages from the first PDF. Drag the thumbnail pages from the other open PDFs into this sidebar in the order you want them. Once all pages are arranged, go to File > Export As, choose PDF as the format, and save the merged file with a new name.
Merging PDFs on Windows using Print to PDF
Windows doesn't have a built-in merge tool like Mac's Preview, but you can use the Print to PDF feature to combine files one at a time. Open the first PDF in any PDF reader (Microsoft Edge, Adobe Reader, or Windows Preview all work). Go to File > Print, then select "Microsoft Print to PDF" as your printer.
In the print dialog, you can select specific pages or print all of them. Click Print and save the file with a temporary name. Then open the second PDF, print it to PDF again, but this time append the pages to the first file if your PDF reader offers that option. Most don't, so you'll end up with separate files that you then need to merge using a dedicated tool.
This method is clunky for more than two or three files. If you're doing this regularly on Windows, move to a dedicated tool instead.
Using free desktop software: PDFtk and Ghostscript
PDFtk is a command-line tool that merges PDFs quickly and works on Windows, Mac, and Linux. Download it from pdftk.com, install it, then open your terminal or command prompt. The command to merge files is straightforward: pdftk file1.pdf file2.pdf file3.pdf cat output merged.pdf. Replace the filenames with your actual PDF names, and the merged result saves as merged.pdf in the same folder.
Ghostscript is more powerful but steeper to learn. It's used by many professional PDF tools behind the scenes. On Windows, download from ghostscript.com and install it. On Mac, install it via Homebrew if you have that set up. The merge command is: gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=merged.pdf file1.pdf file2.pdf file3.pdf. Both tools are free and don't send your files anywhere online.
Using web-based tools: ILovePDF and Smallpdf
ILovePDF (ilovepdf.com) and Smallpdf (smallpdf.com) are browser-based tools that require no installation. Go to either site, click the merge option, upload your PDFs by dragging them into the browser window or clicking to select files. Arrange them in the order you want by dragging the thumbnails, then click Merge. Download the result to your computer.
These tools are convenient if you're on a shared computer or don't want to install software. The trade-off is that your PDFs are uploaded to their servers temporarily. Both sites claim to delete files after an hour, but if your PDFs contain sensitive information, this may not be the right choice. Check their privacy policies before uploading anything confidential.
Most web tools offer a free tier with limits on file size or number of merges per day. ILovePDF allows up to 30 files per merge on the free version. Smallpdf limits file size to 500 MB on the free tier.
Reordering pages before merging
If you need to rearrange pages within or between PDFs before merging, do that first. Preview on Mac and most web tools let you drag pages around visually. On Windows or Linux, you can use PDFtk to extract specific pages from a PDF before merging: pdftk input.pdf cat 1-5 7 9-end output output.pdf extracts pages 1 through 5, page 7, and pages 9 to the end, skipping page 6 and 8.
If you're working with many PDFs and need precise control over page order, a web tool's visual interface is usually faster than learning command-line syntax. If you're doing this repeatedly as part of a workflow, learning the command-line tools saves time in the long run.
Choosing between methods: a quick comparison
| Method | Best for | Learning curve | Files stay private |
|---|---|---|---|
| Mac Preview | Mac users, any number of files, visual reordering | None | Yes |
| Windows Print to PDF | One-off merges of two files | None | Yes |
| PDFtk | Regular merges, command-line comfort, any OS | Low | Yes |
| Ghostscript | Advanced control, batch processing | Medium | Yes |
| ILovePDF or Smallpdf | Quick one-time merges, visual interface, no install | None | No |
Frequently Asked Questions
Can I merge PDFs that have different page sizes or orientations?
Yes. All the methods listed here will merge PDFs regardless of page size or orientation. The resulting file will contain pages exactly as they were in the originals. If you want to resize or rotate pages before merging, do that in Preview (Mac) or a dedicated PDF editor first, then merge.
What if one of my PDFs is password-protected?
You'll need to remove the password before merging. If it's a password to open the file, you'll be prompted when you try to open it. If it's a password to edit or print, most tools won't let you merge it without removing that restriction first. Use your PDF reader's security settings or a dedicated tool to remove the restriction, then merge.
Does merging PDFs reduce file size or quality?
Merging doesn't compress or change the quality of the PDFs themselves. The merged file will be roughly the sum of the original file sizes. If you want to reduce file size, you'll need to compress the PDFs separately before or after merging using a compression tool.
Can I merge PDFs on my phone or tablet?
Yes, using web-based tools like ILovePDF or Smallpdf through your phone's browser. Some PDF reader apps on iOS and Android also have merge features built in. Check your app's menu or settings. Desktop tools like PDFtk don't work on phones without additional setup.
Is it safe to use web-based PDF tools with sensitive documents?
Web tools upload your files to their servers, which means they leave your device. If your PDFs contain confidential information, use a desktop method instead: Preview on Mac, PDFtk on any OS, or Ghostscript. These keep your files on your computer the entire time.