The fastest way depends on what you already have installed

You can combine PDFs using free software that's already on your computer, paid desktop programs, or online tools that work in your browser. The method that takes the least time depends on whether you own the PDFs, how many you're combining, and whether you need to do this once or regularly.

On Windows, the built-in Print to PDF feature works for small jobs. On Mac, Preview handles it without installing anything. If you combine PDFs often, a dedicated tool like Adobe Acrobat Pro or free alternatives like PDFtk or Ghostscript will be faster than repeating the same steps each time. Online tools like ILovePDF or Smallpdf work from any device but require uploading your files to their servers.

Key Takeaways

  • Windows and Mac both have free built-in tools: Print to PDF on Windows, Preview on Mac.
  • Online tools like ILovePDF or Smallpdf combine PDFs in your browser without installing software, but your files upload to their servers.
  • Desktop software like Adobe Acrobat Pro, PDFtk, or Ghostscript is faster for repeated combining and keeps files on your computer.
  • The order matters: most tools let you drag files into the order you want before combining.
  • Some tools can extract pages from PDFs before combining, so you don't have to combine entire documents.

Using Windows Print to PDF

On Windows 10 and later, you can combine PDFs by printing them to a single file. Open the first PDF in any program that can display it — Adobe Reader, Microsoft Edge, or Windows Photos all work. Go to File, then Print. In the printer dropdown, select "Print to PDF" or "Microsoft Print to PDF".

Print the first document. Then open the second PDF, print it the same way, but this time choose "Print to existing PDF" or append it to the file you just created. Windows will ask where to save and what to name the combined file. Repeat for each PDF you want to add. This method works but is slower than dedicated tools because you're printing each document separately.

Using Mac Preview

On Mac, Preview is built in and handles PDF combining directly. Open Preview, then go to File and select "Open". Hold Command and click each PDF you want to combine — Preview will open them all in one window. In the sidebar on the left, you'll see thumbnails of every page from every PDF. Drag the thumbnails into the order you want them.

Once they're in the right order, go to File, then Export As. Choose PDF as the format and name your combined file. Preview saves it when ready. This is the fastest method on Mac because you see all pages at once and can reorder them before saving.

Online tools: ILovePDF, Smallpdf, and similar services

Online PDF combiners work in your web browser without installing anything. Go to ILovePDF.com or Smallpdf.com, find the "Merge PDF" option, and click it. You'll see a box where you can drag and drop PDF files or click to browse your computer. Add all the PDFs you want to combine.

The tool will show you thumbnails of each page. Drag them into the order you want. Click the Merge or Combine button. The tool processes the file on its servers and gives you a read link. The main trade-off is that your PDFs upload to someone else's server — check the site's privacy policy if the documents contain sensitive information. Most of these services keep files for a few hours, then delete them automatically.

Desktop software for regular combining: Adobe Acrobat Pro and free alternatives

If you combine PDFs regularly, a desktop program saves time. Adobe Acrobat Pro costs a monthly subscription and includes a Combine Files tool that's straightforward: open Acrobat, click Tools, select Combine Files, add your PDFs in order, and click Combine. The file stays on your computer and processes faster than online tools.

Free alternatives exist. PDFtk (available for Windows and Mac) and Ghostscript (command-line tool for advanced users) both combine PDFs without a subscription. PDFtk has a graphical interface where you can drag files into order. Ghostscript requires typing commands but is powerful if you're comfortable with that. These tools are free but have steeper learning curves than Adobe or online tools.

Extracting pages before combining

If you don't want to combine entire PDFs — only certain pages from each — most tools let you extract first. In Preview on Mac, select the pages you want (Command-click each thumbnail), then export just those pages as a new PDF. Then combine the extracted PDFs using the method above.

Online tools like ILovePDF show page thumbnails after you upload. You can delete the pages you don't want before combining. Adobe Acrobat Pro has an Extract Pages tool under Tools. This approach takes longer but gives you control over what ends up in the final file.

What to check before you combine

Before combining, make sure all PDFs are in the order you want. Most tools show you a preview, so check that page 1 of the combined file is actually the first page you need. If a PDF has blank pages or pages you don't want, extract them out first rather than combining and then trying to remove them later.

Check the file size of the combined PDF after it's created. If you're combining many large PDFs, the result might be too big to email or upload. Some tools can compress PDFs as part of the combining process — look for a compression option if file size is a concern. Test opening the combined PDF in the program you'll use it in (Adobe Reader, your web browser, or whatever else) to make sure it displays correctly before you rely on it.

Frequently Asked Questions

Can I combine 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 or A4. If that looks wrong, you can resize pages before combining using Adobe Acrobat Pro or online tools that offer a resize option.

What if one of my PDFs is password-protected?

You'll need to remove the password first. If it's a password you know, open the PDF in Adobe Reader or Preview, go to File, and look for an option to remove security or permissions. If you don't know the password, most combining tools won't work until you remove it.

Does combining PDFs reduce the quality?

No. Combining is just putting files together — it doesn't re-compress or change the images or text. The combined PDF will have the same quality as the originals. Online tools sometimes offer compression as an optional step, but that's separate from combining.

Can I combine PDFs on my phone?

Yes, using online tools. Open ILovePDF or Smallpdf in your phone's browser, upload the PDFs, and combine them. Some phones have built-in PDF readers with basic combining features — check your phone's file manager or PDF app. Desktop tools are faster for large jobs, but online tools work anywhere you have internet.

What's the file size limit for online tools?

Most free online tools accept files up to 100 MB to 500 MB per upload, though limits vary by service. Check the tool's website for its specific limit. If your PDFs are larger, use a desktop tool instead, or split them into smaller batches and combine in stages.