The fastest way to combine PDFs depends on what you have installed

You can merge PDFs using free software that's already on your computer, a free online tool, or paid software if you're doing this regularly. Windows and Mac both come with built-in options that work without downloading anything. If you prefer not to use your browser for uploads, desktop software like PDFtk or Ghostscript runs locally on your machine. The choice comes down to how many files you're merging, whether you need to reorder pages, and whether you want the tool to remember your settings for next time.

Most people can finish a merge in under five minutes using any of these methods. The main difference is convenience: built-in tools take longer per file but require no setup, while dedicated PDF software is faster if you're merging dozens of documents a week.

Key Takeaways

  • Windows 10 and 11 can merge PDFs through File Explorer by opening each PDF and printing to a new PDF, or by using the Print to PDF feature with multiple files selected.
  • Mac users can open PDFs in Preview, drag pages from one document into another, and save the result without installing anything.
  • Free online tools like ILovePDF, Smallpdf, and PDF Merge let you upload multiple files and read the combined result in seconds, but require an internet connection.
  • Desktop software like PDFtk, Ghostscript, or Sejda Desktop is faster for regular merging and keeps your files on your computer instead of uploading them.
  • Most tools let you reorder pages before merging, but check whether the software preserves links, bookmarks, and form fields in the final file.

Merging PDFs on Windows without installing software

Windows 10 and 11 include a built-in PDF printer that can combine files. Open File Explorer and select all the PDF files you want to merge. Right-click and choose "Print". In the print dialog, change the printer to "Microsoft Print to PDF" and click Print. Windows will ask where to save the new file. This creates a single PDF, but the order depends on how your files are sorted in the folder — you cannot reorder pages this way.

If you need to control the order, open the first PDF in Microsoft Edge or Adobe Reader, then print it to PDF. Before you print, go to the print dialog and look for an option to add more pages or documents. Edge does not have this built-in, so you would need to print each file separately and then use an online tool to combine them. This method is slower but gives you full control over page order.

A faster Windows option is to use the free desktop tool PDFtk Server. read it from the PDFtk website, install it, and then open Command Prompt. Type pdftk file1.pdf file2.pdf file3.pdf cat output merged.pdf, replacing the filenames with your own. This combines the files in the order you list them and takes seconds once you learn the command.

Merging PDFs on Mac using Preview

Mac's Preview app can merge PDFs without any downloads. Open Preview and go to File > Open. Select the first PDF you want to merge. Then go to File > Open Again and select the second PDF — it will open in a new Preview window. In the first window, go to View > Thumbnails to see all pages as small images on the left side. Click and drag the thumbnail pages from the second window into the first window's thumbnail panel. Arrange them in the order you want, then go to File > Save.

This method works for any number of files. You can drag pages from multiple PDFs into one document and reorder them by dragging the thumbnails around. Preview preserves most formatting, though it may lose interactive elements like form fields or embedded links. If you need those features to survive the merge, use a dedicated PDF tool instead.

Using free online tools for quick merges

Online PDF mergers work on any computer with a web browser and do not require installation. Go to ILovePDF.com, Smallpdf.com, or PDFMerge.com. Click the button to select files from your computer, choose all the PDFs you want to combine, and click Merge. The tool uploads your files, combines them, and gives you a read link within seconds. Most of these tools let you drag files to reorder them before merging.

The trade-off is that your files are uploaded to someone else's server. If your PDFs contain sensitive information, check the website's privacy policy. Most reputable tools delete your files after a few hours, but you are trusting their word. ILovePDF and Smallpdf both offer paid plans that add features like batch processing and scheduled deletions, but the free versions work fine for occasional merging.

Online tools usually preserve page content but may lose bookmarks, form fields, or embedded links. Test with one non-critical file first if those features matter to you. If the merged file is missing something important, try a desktop tool instead.

Desktop software for regular or complex merging

If you merge PDFs more than once a week, desktop software is faster and keeps your files private. PDFtk Server is free and works on Windows, Mac, and Linux through the command line. Ghostscript is also free and more powerful, though it has a steeper learning curve. Sejda Desktop is free for up to three files per month and offers a paid version for unlimited merging.

These tools let you merge, reorder, rotate, and compress PDFs in batches. You can write a script that automatically merges all PDFs in a folder every morning, or set up a workflow that combines files as soon as they arrive. They preserve bookmarks, links, and form fields better than online tools because they do not re-encode the PDF data.

For Windows users who want a graphical interface instead of command-line tools, PDF-XChange Editor has a free version that includes merging. On Mac, Coherent PDF is paid but fast and reliable. Choose based on whether you prefer clicking buttons or typing commands, and whether you need advanced features like splitting, watermarking, or compression.

What happens to links, bookmarks, and form fields when you merge

Different tools handle special PDF features differently. Links to websites usually survive any merge. Bookmarks (the navigation panel on the left side of a PDF) may be lost or combined awkwardly. Form fields that let you type into boxes often break unless the tool is designed to preserve them.

Test with a copy of your file first if any of these features are important. Open the merged PDF and check whether links still work, whether you can still fill in forms, and whether bookmarks point to the right pages. If something broke, try a different tool — desktop software like PDFtk and Ghostscript preserve these features more reliably than online tools.

If you are merging PDFs that contain form fields and need the forms to work in the final file, avoid online tools and use desktop software instead. Some tools like Adobe Acrobat Pro can flatten forms (convert them to regular text) during the merge, which is useful if you want to lock the data in place.

Reordering pages before and after merging

Most merging tools let you arrange files before combining them. Drag the files into the order you want, and the tool will combine them in that sequence. If you need to reorder individual pages within the merged file, you have two options: reorder before merging (if the tool supports it), or merge first and then use a separate tool to rearrange pages.

Preview on Mac and most online tools show you thumbnails of every page and let you drag them into a new order before saving. PDFtk and Ghostscript require you to specify page ranges in the command, which is more precise but less visual. If you have a 50-page PDF and only want pages 3 through 7 from it, you can tell PDFtk to extract just those pages before merging.

If you merge first and then realize you need different page order, use the same tool you used to merge — most can open the merged file and let you rearrange pages. This is slower than getting the order right the first time, so spend 30 seconds arranging your files before you hit the merge button.

Frequently Asked Questions

Can I merge PDFs that have different page sizes?

Yes. Most tools will combine them as-is, so you might end up with a document where some pages are letter-size and others are legal-size. If you need all pages to be the same size, use a tool like Ghostscript or PDFtk that can resize pages during the merge, or resize them separately before merging.

What if one of my PDFs is password-protected?

You cannot merge a password-protected PDF without entering the password first. Open it in your PDF reader, enter the password, and save an unprotected copy. Then merge the copy with your other files. Some tools like PDFtk can handle password-protected files directly if you provide the password in the command.

Will merging reduce the file size or quality?

Most tools preserve the original quality and file size. Online tools sometimes compress images slightly to speed up uploads, which can reduce quality slightly. If file size matters, use desktop software like Ghostscript, which can compress during the merge without losing much quality.

Can I merge PDFs on my phone?

Yes, using online tools or mobile apps. On iPhone, the Files app can open PDFs in different apps, but merging requires a dedicated app like PDF Merger or Smallpdf's mobile app. On Android, apps like PDF Merge and Sejda work similarly. Mobile merging is slower than desktop tools and works best for small batches.

How do I merge PDFs automatically on a schedule?

Use desktop software like Ghostscript or PDFtk with a script. On Windows, create a batch file that runs the merge command every morning. On Mac, use a cron job or Automator workflow. This requires some technical knowledge, but it is the only way to automate merging without paying for enterprise software.