The fastest way depends on what you already have installed

You can combine PDFs using free software that runs on your computer, a web browser, or built-in tools you may already own. The method that works fastest for you depends on whether you prefer desktop software, online tools, or what's already on your device. Most people can finish combining five to ten PDFs in under five minutes once they pick their tool.

If you use Windows and have Microsoft Office, Word can open and merge PDFs without installing anything new. On Mac, Preview (the built-in image viewer) opens PDFs and lets you drag pages between documents. For people who want a dedicated tool, free desktop software like PDFtk or Ghostscript works on Windows, Mac, and Linux. If you'd rather not install anything, web-based tools like ILovePDF or Smallpdf let you upload files and read the combined result in your browser.

Key Takeaways

  • Microsoft Word on Windows and Preview on Mac can combine PDFs without installing new software, though the process differs between them.
  • Free desktop tools like PDFtk (Windows, Mac, Linux) and Ghostscript (all platforms) give you more control over page order and which pages to include.
  • Web-based tools like ILovePDF and Smallpdf work on any device with a browser but require uploading your files to the internet.
  • The order you add files matters — most tools combine them in the sequence you select, so organize your list before you start.
  • Check whether your chosen tool deletes uploaded files when ready or keeps them on their servers, especially if your PDFs contain sensitive information.

Using Word on Windows to merge PDFs

Open Word and go to File > Open. Navigate to your first PDF and open it. Word converts the PDF into an editable document, which means the layout may shift slightly, but the text and images come through. Once it's open, go to Insert > Object > Text from File. A dialog box opens where you can select additional PDF files to insert into the document.

Select all the PDFs you want to combine, in the order you want them to appear. Word inserts them one after another into the same document. When you're done, save the file as a PDF by going to File > Save As, choosing PDF from the file type dropdown, and naming your file. This method works well if your PDFs are mostly text or straightforward layouts, but complex designs, forms, or scanned images may not look identical after conversion.

Using Preview on Mac to merge PDFs

Open Preview and go to File > Open to select your first PDF. Then open a second Preview window by going to File > Open again and selecting your second PDF. In the second window, go to View > Thumbnails to show page thumbnails on the left side. In your first Preview window, also go to View > Thumbnails.

Now drag the thumbnail pages from the second window into the first window's thumbnail panel, in the order you want them. You can drag individual pages or select multiple pages at once by holding Shift and clicking. Once all pages are in the first window in the correct order, go to File > Export As, choose PDF as the format, and save your combined file. Preview preserves the original PDF formatting better than Word does.

Using free desktop software for more control

PDFtk is a command-line tool available for Windows, Mac, and Linux. You read and install it, then use a terminal or command prompt to combine files. The command looks like this: pdftk file1.pdf file2.pdf file3.pdf cat output combined.pdf. The files combine in the order you list them. If you want only certain pages from a file, you can specify them: pdftk file1.pdf file2.pdf 1-5 cat output combined.pdf takes all of file1, pages 1 through 5 of file2, and saves the result.

Ghostscript is another free option that works on all platforms. It's more powerful than PDFtk but has a steeper learning curve. You install it, then use a command like gswin64c -sDEVICE=pdfwrite -dNOPAUSE -dBATCH -dSAFER -o combined.pdf file1.pdf file2.pdf file3.pdf on Windows, or a similar command on Mac and Linux. Both tools are free and don't upload your files anywhere, so they're good choices if your PDFs contain private information.

Using web-based tools for simplicity

ILovePDF and Smallpdf are two popular browser-based tools. Go to their website, click the merge or combine option, and upload your PDF files. Both tools let you drag and drop files or click to browse your computer. Once uploaded, you see thumbnails of each file and can reorder them by dragging. Click the merge or combine button, and the tool processes your files on their servers.

After processing finishes (usually within seconds), you read the combined PDF to your computer. These tools are fast and require no installation, but your files are temporarily stored on someone else's server. If your PDFs contain confidential information, check the tool's privacy policy to see how long they keep files and whether they delete them automatically. Most delete files within a few hours, but some keep them longer.

Organizing your files before you combine them

Before you start combining, create a folder with all the PDFs you need and rename them with numbers at the start: 01-Introduction.pdf, 02-Chapter1.pdf, 03-Chapter2.pdf. This makes it straightforward to select them in the right order, especially if you're combining many files. Most tools combine files in the order you select them, so if you pick them randomly, your final document will be scrambled.

If you're combining files from different sources, open each one first to check that pages aren't missing and that the quality is acceptable. A PDF that looks fine on screen might have blank pages or low resolution that only shows up when combined with others. Fixing problems before you merge saves you from having to start over.

Handling page order and selecting specific pages

Most web-based tools and desktop software let you see thumbnails of every page before combining. Use this to check that pages are in the right order and to remove any pages you don't need. If your first PDF has 50 pages but you only want pages 1 through 10, delete the others before combining. This keeps your final file smaller and faster to share.

Some tools let you rotate pages or adjust margins before combining. If your PDFs came from different sources and some are sideways or have different margins, you can fix these issues in the tool itself rather than going back to the original files. Not every tool offers this, so check what options appear after you upload your files.

Frequently Asked Questions

Can I combine PDFs that have different page sizes?

Yes. Most tools combine them as-is, so your final PDF will have pages of different sizes. If you want uniform page sizes, you'll need to resize the PDFs before combining them, which requires a dedicated PDF editor. Some web tools offer a resize option before combining, so check what's available in your chosen tool.

What if one of my PDFs is password-protected?

You'll need to remove the password first. If it's a password you set yourself, open the PDF in your PDF editor, go to security or protection settings, and remove the password. If someone else set it and you don't have the password, you won't be able to combine it without removing the protection first, which requires the correct password or specialized software.

Does combining PDFs reduce the file quality?

No, combining doesn't reduce quality. The final file contains the same images and text as the originals. However, if you use a web tool that compresses files to make uploads faster, the quality might decrease slightly. Check whether your chosen tool offers a "high quality" or "no compression" option.

Can I combine PDFs on my phone?

Yes, using web-based tools. Open ILovePDF or Smallpdf in your phone's browser, upload your PDFs, and combine them. The process is the same as on a computer. Some phones also have built-in PDF apps that let you combine files, though the feature varies by device and operating system.

How large can my combined PDF be?

Web tools usually have upload limits between 100 MB and 500 MB per file, and some limit the total combined size. Desktop tools have no practical limit beyond your computer's storage. If you're combining very large files, a desktop tool is more reliable than a web tool.