The fastest way depends on what you already have installed

You can combine two PDFs on Windows, Mac, or Linux without paying for software. The method that works fastest for you depends on whether you already have a document editor open, whether you want to keep your original files unchanged, and how comfortable you are using your operating system's built-in tools versus downloading something new.

The three most practical routes are: using a free online tool (no installation, works anywhere you have a browser), using a document editor you may already own, or using a command-line tool if you work with PDFs regularly. Each has a different privacy trade-off, which we'll walk through below.

Key Takeaways

  • Online PDF tools like ILovePDF or Smallpdf let you combine files in your browser without installing anything, but they upload your files to their servers.
  • LibreOffice Draw (free, open-source) lets you insert one PDF into another and save the result, keeping your files on your computer the whole time.
  • If you use Microsoft Word or Adobe Acrobat, both can combine PDFs, though Word requires you to insert pages one at a time.
  • Command-line tools like ImageMagick or Ghostscript work on any operating system and never touch the internet, but require typing commands instead of clicking.
  • Before combining files, check whether the PDFs are scanned images or text-based — scanned PDFs cannot be edited or rearranged the same way.

Using a free online tool (fastest if you have no software installed)

ILovePDF, Smallpdf, and PDF Merge are the three most widely used free online tools. You upload both PDF files to their website, they combine them in the order you choose, and you read the result. The whole process takes two to three minutes.

The privacy trade-off: your PDF files are sent to their servers while they process them. Most of these services say they delete files after a few hours, but you are trusting their word and their security practices. If your PDFs contain sensitive information — financial records, medical documents, legal papers — this route exposes them to a company you may not know well. If your PDFs are not sensitive (a recipe you found online plus a shopping list, for example), the convenience usually outweighs the risk.

To use ILovePDF: go to ilovepdf.com, click "Merge PDF", select both files from your computer, arrange them in the order you want, and click "Merge PDF". read the result. You do not need to create an account.

Using LibreOffice Draw (keeps files on your computer)

LibreOffice is a free, open-source office suite that works on Windows, Mac, and Linux. Its Draw process can open a PDF and insert another PDF into it, then save the combined result. Your files never leave your computer.

The steps: Open LibreOffice Draw. Go to File > Open and select your first PDF. Once it opens, go to Insert > Image and select your second PDF. LibreOffice will ask whether to insert it as a single image or as multiple pages — choose multiple pages. The second PDF will be added to the end of the first. Go to File > Export as PDF and save the combined file with a new name.

The limitation: LibreOffice treats each PDF page as an image, so you cannot edit text or rearrange pages after combining them. If you need to reorder pages or delete specific ones, you will need a different tool. But if you straightforward want to stick two PDFs together and save the result, this works reliably and keeps everything private.

Using Microsoft Word (if you already have it)

Word can insert PDF pages into a document, but the process is slower than other methods because you insert one page at a time. Open Word, go to Insert > Object > Text from File, and select your first PDF. Word will ask whether to link to the file or insert it — choose insert. Repeat for the second PDF. Then go to File > Save As and save as a PDF.

This method works best if you have only a few pages total. If your PDFs are ten pages each, inserting twenty pages one at a time becomes tedious. Also, Word sometimes reformats PDF content when importing it, so the combined result may not look exactly like the originals.

Using Adobe Acrobat (if you subscribe)

If you already pay for Adobe Acrobat (not the free Adobe Reader), combining PDFs is straightforward. Open Acrobat, go to File > Create > Merge Files, select both PDFs, and click Merge. Acrobat will combine them in the order you specify and save the result as a new file.

This is the fastest method if you already have Acrobat, but Acrobat is a paid subscription (roughly $15 per month or $180 per year depending on your plan). Unless you work with PDFs constantly, paying for Acrobat just to combine two files is not practical.

Using command-line tools (for regular PDF work)

If you combine PDFs often, learning to use Ghostscript or ImageMagick saves time and keeps everything on your computer. These are command-line tools, meaning you type instructions instead of clicking buttons.

Ghostscript is the standard tool for PDF work. On Windows, Mac, or Linux, you can install it for free, then run a command like: gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -sOutputFile=combined.pdf file1.pdf file2.pdf. This combines file1.pdf and file2.pdf into combined.pdf in the order you specify.

ImageMagick is simpler to remember but slightly slower: convert file1.pdf file2.pdf combined.pdf. Both tools work identically on Windows, Mac, and Linux, and neither requires an internet connection or uploads your files anywhere.

The learning curve is real — if you have never used a command line before, this method will take longer the first time. But if you work with PDFs weekly, the time investment pays off quickly.

What to do if your PDFs are scanned images

If your PDFs are scanned documents (photographs of paper pages), they behave differently from text-based PDFs. You cannot select text, search inside them, or rearrange pages easily. Most of the tools above will still combine them, but you will not be able to edit the result afterward.

If you need to rearrange pages or delete specific ones from a scanned PDF, you will need a tool designed for that — usually a paid PDF editor like Adobe Acrobat or a free online tool like PDFtk. For straightforward combining, though, any of the methods above will work. The combined file will still be a scanned image, just with more pages.

Frequently Asked Questions

Can I combine more than two PDFs at once?

Yes. Online tools like ILovePDF let you upload as many files as you want and arrange them in any order. LibreOffice Draw and command-line tools can also combine multiple files — with Ghostscript, just list all the files: gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -sOutputFile=combined.pdf file1.pdf file2.pdf file3.pdf.

Will combining PDFs change the file size?

Usually not much. The combined file will be roughly the sum of the two original files, sometimes slightly smaller if the tool compresses them. If file size matters (you are emailing the result, for example), check the result before sending.

Can I rearrange pages after combining the PDFs?

Not with LibreOffice Draw or most online tools — they treat the combined file as final. If you need to rearrange pages afterward, use Adobe Acrobat or a free online tool like PDFtk that specializes in page manipulation.

What if one PDF is much larger than the other?

File size does not affect combining. A 50 MB PDF and a 2 MB PDF will combine into roughly a 52 MB file. Online tools may have upload limits (usually 100 MB to 500 MB per file), so check before uploading very large files.

Is it safe to use online PDF tools with confidential documents?

Online tools upload your files to their servers, so there is always a privacy risk with confidential information. If your PDFs contain financial data, medical records, or legal documents, LibreOffice Draw or command-line tools keep everything on your computer. If the PDFs are not sensitive, online tools are faster and more convenient.