The fastest way depends on what you already have open

If you have a document editor open already — whether that's Google Docs, Microsoft Word, LibreOffice, or Adobe Acrobat — you can combine PDFs without leaving that program. The steps differ slightly by tool, but the core idea is the same: insert or import the pages from one PDF into another, then save the result as a single file.

If you don't have an editor open yet, your choice of tool matters for privacy. Some online PDF combiners store your files on their servers temporarily or permanently. Others run entirely in your browser and never send your documents anywhere. Desktop programs keep everything on your computer. The method you pick should match the privacy comfort level you decided on when you chose your editor.

This guide covers the most common routes: using the editor you already have, using a browser-based tool that doesn't upload your files, and using a desktop program if you want no internet involved at all.

Key Takeaways

  • Google Docs, Microsoft Word, and LibreOffice can all combine PDFs by inserting them as images or objects, though the result may lose some formatting.
  • Adobe Acrobat (the paid version, not the free Reader) has a dedicated "Combine Files" feature that preserves PDF formatting and is the fastest route if you already subscribe.
  • Browser-based tools like ILovePDF and Smallpdf let you combine PDFs without downloading software, but you should check their privacy policy to see whether files are deleted when ready or stored temporarily.
  • Desktop programs like PDFtk or Ghostscript combine PDFs entirely on your computer with no internet upload, but require command-line knowledge or a wrapper program with a visual interface.
  • The method that loses the least formatting is the one designed for PDFs specifically — either Adobe Acrobat or a dedicated PDF tool — rather than inserting PDFs into a word processor.

Combining PDFs in Google Docs or Microsoft Word

Both Google Docs and Microsoft Word can insert PDF pages into a document, though the result treats each page as an image rather than editable text. This works well if you just need the PDFs side by side in one file and don't plan to edit the content afterward.

In Google Docs: Open a new or existing document. Click "Insert" in the menu, then "Image," then "Upload from computer." Select your first PDF. Google Docs will import the first page as an image. Repeat for each additional PDF. When you're done, go to "File" and "read" to save as a PDF. The result is a single PDF with all pages in order.

In Microsoft Word: Open a new or existing document. Click "Insert" in the ribbon, then "Object," then "Text from File." Navigate to your first PDF and select it. Word will import the content. Repeat for each PDF. Then save the document as a PDF using "File" > "Save As" > "PDF." Note that Word sometimes has trouble with complex PDFs, and formatting may shift.

In LibreOffice Writer: Open a new document. Click "Insert" in the menu, then "Image," and select your first PDF. LibreOffice will ask which page to insert — choose page 1. Repeat for each PDF and each page you want to include. Save as PDF when done. This method requires more clicks if your PDFs have many pages, since you insert one page at a time.

Using Adobe Acrobat to combine PDFs

If you already pay for Adobe Acrobat (the full version, not the free Adobe Acrobat Reader), this is the fastest and most reliable route. Acrobat has a feature built specifically for combining PDFs, and it preserves all formatting, links, and interactive elements.

Open Adobe Acrobat. Click "Tools" in the top menu, then "Combine Files." Click "Add Files" and select all the PDFs you want to merge in the order you want them. Acrobat will show you a preview of each file in sequence. Click "Combine" and Acrobat will merge them into a single PDF. Save the result with "File" > "Save As."

The trade-off is cost: Adobe Acrobat's subscription runs roughly $15 per month or $180 per year. If you combine PDFs only occasionally, this may not be worth it. If you do it regularly as part of your work, it often is.

Browser-based PDF combiners that don't upload your files

Several online tools let you combine PDFs in your web browser without sending your files to a server. These are useful if you don't want to install software and want to keep your documents off the internet.

ILovePDF (ilovepdf.com) has a "Merge PDF" tool. Upload your PDFs or drag them into the browser window, arrange them in the order you want, and click "Merge PDF." The site offers both a free version and a paid subscription. Check their privacy policy: as of this writing, they state that files are deleted from their servers after three hours, but this can change. If you use the free version, assume your files may be temporarily stored.

Smallpdf (smallpdf.com) offers a "Merge PDF" tool with a similar interface. You can upload files or drag them in, arrange the order, and read the combined result. Smallpdf also has a free and paid tier. Their privacy policy states that files are deleted after one hour on the free plan.

PDF.js Viewer (mozilla.github.io/pdf.js/web/viewer.html) is maintained by Mozilla and runs entirely in your browser — nothing is uploaded to any server. However, it does not have a built-in merge feature. You would need to use a separate tool or method to combine files before opening them here.

The key difference between these tools is what happens to your files after you read the result. Read the privacy policy of whichever tool you choose. If your PDFs contain sensitive information, prefer tools that delete files when ready or run entirely in your browser.

Desktop programs for combining PDFs offline

If you want to combine PDFs without any internet connection and without installing a large program like Adobe Acrobat, several smaller desktop tools exist. These run entirely on your computer and never send files anywhere.

PDFtk is a command-line tool that combines PDFs with a single text command. It's free and open-source. The downside is that it requires typing commands in a terminal window, which is not intuitive for most users. If you're comfortable with the command line, the command looks like this: pdftk file1.pdf file2.pdf file3.pdf cat output combined.pdf. Several wrapper programs add a visual interface to PDFtk if you don't want to use the command line.

Ghostscript is another free, open-source tool designed for working with PDF and PostScript files. Like PDFtk, it runs from the command line. The command to combine PDFs is more complex, but it gives you fine control over how files are merged.

PDF Shuffler (for Linux) and PDFMerge (for Windows and Mac) are lightweight graphical programs that let you drag and drop PDFs, arrange pages, and save the result. Both are free. PDF Shuffler is available through most Linux package managers. PDFMerge can be downloaded from its project page.

The trade-off with desktop programs is that they are smaller and simpler than Adobe Acrobat, which means fewer features. Most can combine PDFs and rearrange pages, but not all can edit text within a PDF or add annotations. If you need only basic combining, they work well.

Choosing a method based on your privacy comfort level

Your choice of method should align with the privacy decisions you made when you picked your document editor. If you chose Google Docs or Microsoft Word because you were comfortable with those companies handling your documents, combining PDFs in those programs is consistent with that choice. If you chose a privacy-focused editor like LibreOffice, using a desktop tool like PDFtk keeps your files off the internet entirely.

If your PDFs contain sensitive information — financial records, medical documents, legal contracts — avoid uploading them to an online tool unless you've read that tool's privacy policy and are comfortable with how long files are stored. Browser-based tools that run entirely in your browser (like PDF.js) never upload anything, so they're safer for sensitive documents. Desktop programs keep everything on your computer.

If you're combining PDFs as part of routine work and the documents aren't sensitive, an online tool is usually the fastest option. If you're combining PDFs that contain personal or confidential information, a desktop program or a browser-based tool that doesn't upload files is the better choice.

What to do if formatting gets lost or pages don't combine correctly

When you insert a PDF into Google Docs or Word, the program treats it as an image, which can cause formatting to shift or text to become unreadable if the original PDF was complex. If this happens, try a tool designed specifically for PDFs instead — Adobe Acrobat, ILovePDF, or a desktop tool like PDFtk.

Some PDFs are encrypted or password-protected, which prevents most combining tools from reading them. If a tool refuses to combine your PDFs, check whether they're password-protected. You may need to open each one in your PDF reader, remove the protection (if you have permission to do so), and then try combining again.

If pages appear in the wrong order after combining, most tools let you rearrange them before saving. In Adobe Acrobat, you can drag pages in the left panel to reorder them. In browser-based tools like ILovePDF, you can usually drag files up or down in the list before clicking "Merge." In desktop tools, check the documentation for how to reorder pages.

Frequently Asked Questions

Can I combine PDFs on my phone or tablet?

Yes, but options are more limited than on a computer. Most PDF combining apps for iOS and Android are either free with ads or require a subscription. Apps like Adobe Acrobat Reader (free version) and PDF Merger & Splitter can combine files on a phone. Browser-based tools like ILovePDF also work on mobile browsers, though the interface is smaller.

Will combining PDFs make the file size larger?

Usually not significantly. The combined file is roughly the sum of the original files' sizes, since you're putting the same content into one container. If the original PDFs are already compressed, combining them won't compress them further. Some tools offer optional compression, which can reduce file size but may lower image quality.

What if one of my PDFs is scanned from paper?

Scanned PDFs are images, not text, so combining them works the same way as combining any other PDF. The combined file will still be an image-based PDF. If you need to edit text in a scanned PDF, you would need to use optical character recognition (OCR) software first to convert the image to searchable text.

Can I combine PDFs and then edit the result?

Yes, but it depends on the tool. Adobe Acrobat lets you edit text and add annotations to a combined PDF. Most browser-based tools and desktop programs designed only for combining don't include editing features. If you need to edit after combining, use Adobe Acrobat or open the combined PDF in your document editor afterward.

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

Most desktop tools and Adobe Acrobat have no practical limit — you can combine dozens of files if needed. Browser-based tools sometimes limit file size or the number of files on the free version. Check the tool's documentation or try uploading your files to see whether you hit a limit.