The fastest way depends on what you already have installed

You can merge PDFs using software you likely already own — Preview on Mac, Microsoft Edge on Windows, or a free tool like PDFtk or ILovePDF online. The method that works best depends on whether you want to keep files on your computer, use a web browser, or install new software. Most people can finish in under five minutes using whichever tool matches their setup.

If you came here from the privacy guide, remember that online tools send your files to someone else's server, while desktop software keeps them local. That trade-off matters more for sensitive documents than for combining receipts or meeting notes.

Key Takeaways

  • Mac users can drag PDFs into Preview, arrange them in the sidebar, and export as a single file without installing anything.
  • Windows users can open PDFs in Microsoft Edge, use the print function to combine them into one file, or use free desktop software like PDFtk.
  • Online tools like ILovePDF or Smallpdf work in any browser but upload your files to their servers, which matters if the PDFs contain private information.
  • Most desktop tools let you reorder pages before merging, so you can arrange documents in the order you need.
  • The file size of your merged PDF depends on the original files — combining ten 5 MB PDFs creates roughly a 50 MB file.

Merging PDFs on Mac using Preview

Open the first PDF in Preview (the default PDF viewer on Mac). Go to the sidebar on the left — if you don't see it, click View and select Sidebar. Drag the other PDF files directly into that sidebar below the first one. The pages from each file will appear as thumbnails you can rearrange by dragging.

Once all files are in the sidebar in the order you want, go to File and select Export As. Choose a name and location, make sure the format is set to PDF, and click Save. Preview combines all the pages into a single file in the order they appear in the sidebar.

Merging PDFs on Windows using Microsoft Edge

Open the first PDF in Microsoft Edge. Click the three dots in the top right corner and select Print. In the print dialog, change the printer to "Print to PDF" or "Microsoft Print to PDF" (depending on your Windows version). Under More Settings, look for an option to add files or combine documents — Edge's print dialog sometimes includes this feature.

If your version of Edge doesn't show a combine option in the print dialog, use a free desktop tool instead. PDFtk Server (available from pdftk.com) runs from the command line and merges files with a single command, though it requires typing rather than clicking. For a graphical interface, try Sejda Desktop, which works similarly to the online version but keeps files on your computer.

Using online tools when desktop software isn't an option

ILovePDF, Smallpdf, and similar online tools let you upload multiple PDFs, arrange them, and read the merged result without installing anything. Go to the site, click the merge option, select all the PDFs you want to combine, and drag them into the order you need. Click Merge and read the result.

The trade-off is that your files travel to the company's servers during the process. If the PDFs contain tax returns, medical records, or other sensitive information, a desktop tool keeps that data on your computer instead. Most online tools delete files after a few hours, but you're relying on their privacy policy rather than your own control.

Arranging pages before you merge

All the methods above let you see pages as thumbnails and drag them into a different order before finalizing the merge. This matters if you're combining documents that need to appear in a specific sequence — for example, a cover page, then chapters, then an appendix.

In Preview on Mac, drag thumbnails in the sidebar. In online tools, drag the file boxes themselves to reorder which document comes first, or open each file after uploading to rearrange individual pages within it. Some tools also let you delete pages you don't need before merging, which reduces the final file size.

Reducing file size if the merged PDF is too large

A merged PDF is roughly the sum of the original files — combining ten 5 MB PDFs creates a file around 50 MB. If that's too large to email or store, you have two options: compress the merged file afterward, or compress the original PDFs before merging.

Most online merge tools include a compress option after merging. Desktop tools like PDFtk don't compress, but you can use a separate free tool like Ghostscript (command line) or an online compressor afterward. Compression trades quality for size — text stays readable, but images become slightly blurry. For documents that are mostly text, compression usually works fine.

What to do if a PDF won't merge

Occasionally a PDF is locked or corrupted and won't combine with others. Try opening it in a different viewer first — sometimes the file opens in one program but not another. If it opens but still won't merge, try converting it to a different format (like an image or Word document) and then converting back to PDF before merging.

If you're using an online tool and a file repeatedly fails, try uploading it to a different service. Some tools handle unusual PDF formats better than others. For desktop tools, updating to the latest version sometimes fixes compatibility problems with newer PDFs.

Frequently Asked Questions

Can I merge PDFs on my phone?

Yes, using an online tool or an app. Most phone browsers support ILovePDF or Smallpdf, though uploading multiple files on a phone is slower than on a computer. Apps like Adobe Acrobat Reader (free version) and Sejda also merge PDFs on iOS and Android, though some features require a paid subscription.

Does merging PDFs change the quality?

No, merging itself doesn't reduce quality — the merged file contains the exact same pages as the originals. Compression afterward can reduce quality slightly, but merging alone is lossless.

Can I merge PDFs that have different page sizes?

Yes. All the tools above handle mixed page sizes. The merged file will contain each page exactly as it was in the original, so a letter-size page followed by a legal-size page will appear that way in the result.

What if I need to merge the same PDFs regularly?

If you merge the same files repeatedly, a desktop tool with a saved workflow saves time. PDFtk lets you write a script that combines specific files in a set order and runs with one click. Online tools don't offer this, since you upload files each time.

Is there a limit to how many PDFs I can merge at once?

Desktop tools have no practical limit — you can merge hundreds of files if your computer has enough memory. Online tools usually cap merges at 20 to 50 files per session, though you can merge the result with more files afterward if needed.