What does combining PDF files mean?

Combining PDF files simply means combining multiple files into a single file. That sounds simple enough. However, there are numerous nuances around this topic that we ought to examine.

To start things off, we have to note that the ability to combine multiple files into a single PDF is something that is very frequently used and searched for on the internet.

It’s a useful skill to have for anyone working not just with PDFs but also with other office and text-based document formats - for example, Word, Excel, and Powerpoint files.

Combining PDF files is also very relevant for anyone looking to work with images since PDF files often contain images or have even been created by converting an image to a PDF.

Also, note that there are subtle but key differences in exactly how one would go about combining the file. For instance, combining 2 files into 1 file is obviously a thing, but what about combining 3, 5, 10, or more files into a single file?

Furthermore, are you able to rearrange the pages inside the input files and the residing output files? Are you able to use any kind of PDF file or even a non-PDF file in the input files and still receive the combined file?

You get the point - all of those seemingly tiny but actually pretty important distinctions are what makes combining a complex topic. And the examples above do not even scratch the surface of it.

There are a bunch more technical gotchas related to the files- sometimes PDFs are password protected or have been signed with a digital signature, so this presents a challenge to any software trying to combine them.

The orientation of the pages and even the metadata can also play a role towards your results. All of those subtleties are exactly why multiple vendors are able to advertise combining, merging, mixing, arranging, etc.

PDF files, but only a select few are successful in providing a polished solution that meets all possible use cases. PDF Extra has all of those and more on its website!

Why combining PDF files is useful?

First is the question of usefulness and, generally speaking, why someone might want to combine their files and end up with a single file. The obvious thing that comes to mind is the convenience of having just one file and the less clutter that comes with it.

Whilst this is a huge benefit, it’s far from the only one, and there are other scenarios where having just one file is best. For instance, it’s orders of magnitude easier to just open a single file into any kind of editing, file, text, or image manipulation software.

Not only that, but it’s oftentimes the only option for some software, particularly older ones, that do not necessarily play nice with the notion of having a bunch of files opened at once.

Another practical reason is if you’re planning on using your output PDF file into any kind of commercial software that charges on use - a good example here is digitally signing a PDF through a paid SaaS service like DocuSign, IronClad, or similar.

Those kinds of services tend to treat files as atomic contracts and may charge much less for a single contract signature than they would for two of those, not to mention avoiding the nightmare that having your contract split into multiple files would be.

What are the different ways to combine PDFs?

So now that we know about all of the benefits of combining PDFs, the immediate thing that you would notice is that it’s not immediately obvious how to go about actually doing it.

Yes, there are many options advertised on the web, but most of those are very platform or file-specific and not at all user-friendly, and have some serious drawbacks.

First, we have all of the online tools, which, while quick, tend to be very, very low on actual features and more importantly could jeopardize your security. By uploading your file to a Web service, you're always open to the possibility of having your data extracted and harvested somewhere on the Web for eternity.

Or, you know, just straight up not getting your file back. There are even some shady services that seemingly do the combine for free, only to put the output file behind a giant paywall asking for cash once you’re already invested in the process.

Then we have a set of esoteric and hard to use & complex tools - most notably CLIs (command line interfaces) and SDK tools. Essentially those are software packages that are intended for programmers and require some pretty advanced knowledge of how to use and navigate them to get anything done.

Whilst those are used by programmers and some incredibly advanced users, it’s not something we would ever recommend to the average, above average, or even power user. Those tools often have niche licensing schemes where you really never know if you’re in the green or not, so for almost everyone, it really is best to avoid those.

Now we have the bread and butter of combining tools - namely commercial desktop applications. They have dedicated GUI (graphic user interface), tooltips, and often even online help guides and videos to help you do the job.

All of the attractive features we previously discussed, like multiple input files, different formats of input, rearranging pages, and working with protected documents, are exclusively found in commercial desktop apps, including, of course, in PDF Extra.

How to Combine PDFs in Windows?

Follow these steps :

To combine all of your PDFs for free, just visit our website and install the app, and immediately start combining.

1. Immediately after opening the app you will be presented with the “Home Screen”. Just click on Create.

combine pdf windows 1

2. Then click Combine Files. Here you can add or drag & drop any number of files to combine! Or even choose an entire folder if you’re so inclined.

combine pdfs windows 2

Hint: we also support creating the input PDF files for you from an image, scanner, or even from one of our supported office documents: Word, Excel, or Powerpoint, but you have to do so in advance.

3. Use our Drag & Drop UI to rearrange the pages the way you want them to (or simply click Add File to add files manually from your device). You can also delete pages and expand or collapse all pages inside any of the files.

combine pdfs windows 3

combine pdfs windows 5

4. Once you’re done and you’ve arranged your perfect PDF file, just click Combine.
combine pdfs windows 5

5. The resulting file will immediately be opened in PDF Extra and is ready to be signed, shared, or saved (we have 5GB of free storage in MobiDrive).

6. Done!

How to Combine PDFs on a Mac?

If you’re a Mac user, you can still use PDF Extra by downloading Wine which is a free tool that lets apps designed for Windows work on your Mac or Macbook! Or you can get Virtualbox for the entire Windows experience (but virtualized) and still enjoy PDF Extra’s combiner.

If you’re in a pinch and need minimal functionality, newer versions of macOS (starting 2019 with Catalina) offer some built-in functionalities for combining in both the Finder and Preview macOS applications.

So here is how to combine a PDF file with the Preview app on macOS:

1. Duplicate a single file that you intend to use as input - this is essential as Preview saves the files as you go and could override your input files without you noticing.

2. Open the duplicate in Preview.

3. Drag all additional PDF files you want to the Preview sidebar. Optionally you should be able to rearrange the files or delete some of them from the sidebar

4. Once you’re happy with the results, click File > Export to PDF

5. Done!

More PDF combining tips

Combine vs Merge

Two are very often used interchangeably. However, they are not exactly the same in all software vendors. Merging usually can mean that you just glue one PDF to the end of another.

While if you’re combing, you should be able to rearrange the pages. PDF Extra offers a fully featured combine where pages can selectively be added in/out of the file.

Previewing before merging

That's a no-brainer feature, but you would be surprised at how few combiners actually have this. Previewing means that you can actually see what’s in each document and its pages prior to initiating the combine.

This can mean you either see thumbnails for the pages or are able to access a more full-screen preview experience for some or for all pages in documents. Naturally, this works really well with being able to rearrange or delete pages between documents.

PDF Extra has all of those and lets users view the pages, entirety in a full-screen experience.

Avoiding combine side effects

Some side effects that users usually don’t know about can occur in your output file. For one, if any of the files is digitally signed after you combine it with a different file, the result will NOT be signed.

This is an unavoidable consequence of the digital signature process, which is essentially a guarantee of the file’s content at the time of signing. So ergo, if the file changes in any way (i.e., being merged with more pages or files), the content changes, and the digital signature are not valid anymore.
To finish things off, it's a good habit to back up your input files prior to combining them.PDF Extra always keeps the input files intact and never overwrites them. However, as we saw in the macOS example, we can’t say the same of all other software.