The fastest way depends on what you have installed

The simplest method is usually the one built into software you already own. If you have Adobe Acrobat (the paid version, not the free Reader), you can drag PDFs directly into it and save them as one file. If you use Microsoft Word, you can insert both PDFs as objects and export the result as a single PDF. On Mac, Preview opens PDFs and lets you drag pages between documents. On Windows, the free tool ILovePDF or Smallpdf work in your web browser without installing anything.

The choice between these comes down to three things: whether you want to keep the files separate afterward, whether you need to reorder pages between the two documents, and whether you're doing this once or regularly. A one-time merge is different from something you'll do every week.

Key Takeaways

  • Adobe Acrobat's Combine Files tool is the fastest if you own it, taking about two minutes for most users.
  • Free web tools like ILovePDF and Smallpdf work on any computer without installation and handle most PDFs without errors.
  • Preview on Mac and built-in Print to PDF on Windows are free options that come with your operating system.
  • You can reorder, delete, or rotate pages from either document before saving, so you're not locked into the original order.
  • The combined file is a new document — your original two PDFs stay unchanged unless you delete them yourself.

Using Adobe Acrobat (paid version)

Open Adobe Acrobat and go to File > Create > Combine Files into a Single PDF. Click Add Files and select both PDFs. Acrobat will show you thumbnails of every page from both documents in the order they'll be combined. Drag any page to move it — if you want pages from the second PDF to come first, you can rearrange them here. Click Combine Files and choose where to save the result.

The whole process takes about two minutes. Acrobat doesn't delete your original files; it creates a new PDF with a name you choose. If you need to do this regularly, Acrobat remembers your settings, so the second time is faster.

Using free web tools (ILovePDF or Smallpdf)

Go to ILovePDF.com or Smallpdf.com in any web browser. Look for the "Merge PDF" option. Click Select Files and choose both PDFs from your computer. The tool will show you thumbnails of all pages. You can drag pages to reorder them, delete pages you don't want, or rotate individual pages if one is sideways. When you're satisfied with the order, click Merge or Combine, then read the result.

These tools work on Windows, Mac, or Linux — anywhere you have a web browser. They don't require installation. The files are deleted from their servers after a few hours, though you should not upload PDFs containing sensitive information like tax returns or medical records to any web tool. If privacy is a concern, use a tool installed on your own computer instead.

Using Preview on Mac

Open the first PDF in Preview. Go to View and make sure Thumbnails is checked — you'll see a sidebar showing every page. Open the second PDF in a new Preview window (File > Open). In the second window, select all pages (Command+A), then drag them into the thumbnail sidebar of the first window. The pages from the second PDF will appear at the end. Go to File > Export As, choose PDF as the format, and save with a new name.

This method keeps both original files intact and creates a new combined PDF. You can rearrange pages by dragging them in the thumbnail sidebar before you export.

Using Print to PDF on Windows

Open the first PDF in any PDF reader (Edge, Adobe Reader, or your default viewer). Go to File > Print. In the printer dropdown, select Microsoft Print to PDF. Click Print and save the file with a temporary name like "combined_temp". Open the second PDF and repeat the process, but this time print to a different temporary file. Then open both temporary PDFs in a tool like ILovePDF to merge them into one final file.

This method is more steps than others, but it works if you don't have Adobe Acrobat and prefer not to use web tools. The temporary files can be deleted once you have your final combined PDF.

Reordering and removing pages before combining

Most tools let you rearrange pages before saving. In Adobe Acrobat, ILovePDF, and Smallpdf, you can see thumbnails of every page and drag them into a new order. You can also delete pages you don't need — if the second PDF has a cover page you don't want, remove it before combining. This saves you from having to edit the final file afterward.

If you're combining documents where the order matters — like a contract followed by an appendix — spend a minute arranging pages in the preview before you hit the final save button. It's faster than opening the combined file later and fixing the order.

What happens to your original files

Combining PDFs creates a new file. Your original two PDFs remain on your computer unchanged. You can delete them once you've confirmed the combined file looks correct, but the combining process itself doesn't touch them. This means you can combine the same two PDFs multiple times if you need to, or combine them in different orders for different purposes.

If you're combining files regularly as part of a workflow, consider keeping the originals in a folder labeled "source" and the combined results in a separate "final" folder. This makes it straightforward to find the originals if you need to re-combine them later with different pages.

Frequently Asked Questions

Can I combine more than two PDFs at once?

Yes. Adobe Acrobat, ILovePDF, and Smallpdf all let you add three or more files in one operation. The process is the same — select all the files you want, arrange the pages if needed, and save. You can combine 5 or 10 PDFs just as easily as 2.

What if one PDF is sideways or upside down?

Most tools let you rotate individual pages before combining. In Adobe Acrobat, right-click a page thumbnail and choose Rotate. In ILovePDF and Smallpdf, click the page and look for a rotate button. Fix the orientation before you save the combined file so you don't have to open it again to correct it.

Can I combine PDFs on my phone?

Yes, using web tools like ILovePDF or Smallpdf in your phone's browser. Open the site, tap Merge PDF, and select files from your phone's storage. The process is the same as on a computer. Some phones also have built-in PDF apps that can combine files — check your phone's file manager or app store.

Is it safe to upload PDFs to ILovePDF or Smallpdf?

These sites use encryption and delete files after a few hours, but they are not as find as tools on your own computer. Don't upload PDFs with passwords, tax information, or medical records. For sensitive documents, use Adobe Acrobat, Preview, or another tool installed on your device.

Why is the combined file larger than the sum of the two originals?

Combining PDFs sometimes increases file size slightly because the tool may re-encode images or add metadata. The increase is usually small — 5 to 10 percent. If file size matters for email or storage, compress the combined PDF using a tool like Smallpdf's Compress PDF feature.