The fastest way to combine PDFs depends on what you have

You can combine two PDF documents on Windows, Mac, or a web browser without buying software. The method that works fastest for you depends on whether you already have Adobe Reader, whether you own the PDFs or just need to view them, and how many times you plan to do this.

If you have Adobe Acrobat (the paid version, not the free Reader), you can merge PDFs in seconds through the "Combine Files" tool. If you do not own Acrobat, the free options are a web-based PDF tool that works in any browser, or built-in tools on Mac and Windows that take a few more steps but cost nothing.

Key Takeaways

  • Adobe Acrobat's Combine Files tool is the fastest method if you already own it, taking about one minute from start to finish.
  • Free web-based PDF tools like Smallpdf or ILovePDF let you upload two PDFs and download the merged file without installing anything.
  • Mac users can combine PDFs through Preview by opening one document, dragging the second into the sidebar, and exporting as a single file.
  • Windows users can combine PDFs by printing both documents to a single PDF file using the Microsoft Print to PDF printer.
  • The order of pages matters — decide which PDF should come first before you start combining.

Using Adobe Acrobat to merge two PDFs

Open Adobe Acrobat (not Adobe Reader). Click File in the top menu, then select Create, then Combine Files. A window will open asking you to add files.

Click Add Files and browse to the first PDF you want to combine. Select it and click Open. The file will appear in the list. Click Add Files again and select the second PDF. Once both files are in the list, you can drag them to reorder them if needed — whichever is on top will be the first pages in your final document.

Click Combine at the bottom right. Acrobat will merge the files and open the combined document. Go to File and Save As to save it with a new name so you do not overwrite either original file.

Combining PDFs on Mac using Preview

Open the first PDF by double-clicking it. Preview will launch automatically. In the Preview window, look for the sidebar on the left side showing thumbnails of each page. If you do not see it, click View in the top menu and select Thumbnails.

Open the second PDF in a separate Preview window by double-clicking it. Now drag the second PDF's window so you can see both windows at once. Click and drag the thumbnail of the first page from the second PDF's sidebar into the sidebar of the first PDF's window. You can drag it to any position — the pages will insert in the order you drop them.

Once all pages from the second PDF are in the first window's sidebar, go to File and click Export As. Choose a new filename and make sure the format is set to PDF. Click Save. You now have one combined PDF with pages from both documents.

Combining PDFs on Windows using Print to PDF

This method works on Windows 10 and later. Open the first PDF in any PDF reader (Adobe Reader, Microsoft Edge, or Windows Preview all work). Go to File and select Print. In the printer dropdown, select Microsoft Print to PDF. Click Print. A save dialog will open — choose where to save the file and give it a temporary name like "combined_temp". Click Save.

Now open the second PDF in your reader. Go to File and Print again. Select Microsoft Print to PDF. This time, before clicking Print, look for an option that says Print to File or check if there is a checkbox for Append to existing file — this varies by reader. If you see it, check it and select the temporary file you just created. If you do not see this option, you will need to use a different method.

If your reader does not support appending, use a free web tool instead (see the next section). The Print to PDF method works best when your PDF reader has this feature built in.

Using a free web-based PDF tool

Open a web browser and go to Smallpdf.com, ILovePDF.com, or PDF.io. These sites let you combine PDFs without downloading software. Look for a button or link that says "Merge PDF" or "Combine PDF".

Click it and you will see an upload area. Click to browse your files or drag and drop the first PDF into the upload box. Then add the second PDF the same way. The tool will show you thumbnails of both documents. Drag the thumbnails to reorder them if needed — the order shown is the order they will appear in the final file.

Click the Merge or Combine button. The tool will process the files and give you a download link. Click it to save the combined PDF to your computer. These web tools are free for most uses, though some limit how many files you can combine per day or charge for extra features.

What to do if the page order is wrong

If you combined the PDFs and the pages are in the wrong order, you can fix it. Open the combined PDF in Adobe Acrobat or Preview. In Acrobat, go to Tools and select Organize Pages. You will see thumbnails of every page. Click and drag pages to move them to the correct position. When you are done, save the file.

In Preview on Mac, the sidebar shows all pages as thumbnails. Click and drag any page thumbnail to a new position in the list. The document updates instantly. Save the file when you are finished.

If you used a web tool and the order is wrong, you will need to combine them again — most web tools do not let you edit the file after download. Reorder the files before clicking merge the second time.

Frequently Asked Questions

Can I combine more than two PDFs at once?

Yes. Adobe Acrobat, web tools like Smallpdf, and Preview on Mac all let you add three or more PDFs in one operation. The steps are the same — add each file and arrange them in the order you want before merging.

Will combining PDFs change the quality or size of the original documents?

No. Combining PDFs does not compress or reduce the quality of the pages. The file size of the combined PDF will be roughly equal to the sum of the two original files. If one PDF is 5 MB and the other is 3 MB, the combined file will be around 8 MB.

What if one PDF is scanned and the other is digital text?

You can combine them the same way. The merged file will contain both the scanned pages and the text pages in whatever order you arrange them. Scanned pages will remain images, and digital pages will remain searchable text.

Do I need to keep the original PDFs after combining them?

No. Once you have saved the combined PDF, you can delete the original files if you no longer need them. Keep the originals only if you think you might need them separately later.

Which method is fastest if I combine PDFs regularly?

If you do this often, Adobe Acrobat is worth the cost because the Combine Files tool is built in and takes one minute. If you combine PDFs only occasionally, a free web tool is fastest because you do not need to install anything or learn a new program.