How to Combine Multiple PDF Files Into One
Merging a handful of separate PDFs into one document, scanned pages, several reports, a contract and its attachments, is a common enough task that it's worth knowing a reliable free method rather than searching for a new tool every time it comes up. Here's how to do it, with a couple of different approaches depending on how many files you're merging and how often you'll need to.
How Do You Combine Multiple PDFs Into One?
A free dedicated PDF editor like PDF-XChange Editor includes a document merge feature: select your files, arrange them in order, and combine them into one PDF. For an occasional one-off merge, a free online tool works just as well without installing anything.
The core task is the same regardless of tool: gather your separate PDF files, put them in the order you want the final document to read, and combine them into a single output file.
The Reliable Desktop Method
- Open PDF-XChange Editor and go to File > New Document > Combine Files into a Single PDF (or a similarly named option, depending on your version).
- Add your files by clicking Add Files or dragging them into the window.
- Reorder the files by dragging them up or down in the list until they're in the order you want the final document to read.
- Click Combine (or OK) to merge them into a single new document.
- Save the combined file with a new name, keeping your originals untouched.
This method works well if you merge PDFs regularly, since the tool stays installed and ready rather than requiring you to find a website each time.
For an Occasional Merge
For a one-off task, a free online PDF merger avoids installing anything at all.
- Find a reputable free online PDF merge tool.
- Upload your files, usually by dragging them into the browser window.
- Arrange them in order, typically by dragging thumbnails into your preferred sequence.
- Click Merge (or Combine).
- Download the resulting combined PDF.
For anything confidential or sensitive, sensitive business documents, personal identification, financial paperwork, a desktop tool is the safer choice, since it avoids uploading your files to a third-party server. Reserve online tools for non-sensitive content or a genuinely one-off need.
Using Preview's Built-In Merge
Mac users have a genuinely native option with no extra install.
- Open the first PDF in Preview.
- Show the sidebar (View > Thumbnails) to see individual pages.
- Open the second PDF file in a separate Preview window.
- Drag pages from the second document's sidebar into the first document's sidebar, dropping them at the position where you want them to appear.
- Repeat for additional documents, then save the first document, which now contains all the combined pages.
This works well for combining a few documents but can feel slower than a dedicated merge tool if you're regularly combining many files or large documents.
A Manual Fallback
If you don't want to install a PDF editor and don't want to use an online tool, Windows' built-in "Microsoft Print to PDF" feature can combine documents, though it's more manual than the methods above.
- Open each PDF you want to combine, in a PDF reader that supports printing.
- Select all the pages you want from each document (or use a tool that lets you select multiple files to print in sequence).
- Print each in turn, choosing "Microsoft Print to PDF" as the printer and the same output filename with "append" behavior if your specific print driver supports it, or output separate files and use one of the methods above to do the final merge.
In practice, this method is fiddlier than the dedicated tools above and mainly useful as a last resort if you genuinely can't install or access anything else. For anyone doing this more than once, PDF-XChange Editor's dedicated merge feature is worth the small time investment to set up.
Getting the Sequence Right Before You Merge
Before combining, double-check the intended reading order of your final document, cover page first, then sections in sequence, attachments last, for example. All of the methods above let you reorder before finalizing, but it's faster to have your files already named or sorted in the right sequence going in (file01, file02, file03, and so on) than to drag-and-drop reorder a dozen files by hand afterward.
A Fast Method for Power Users
If you're comfortable with a command line and want to merge PDFs as part of a repeatable script rather than a manual click-through process, free command-line tools handle this in a single line. Using a tool like pdftk (PDF Toolkit), a well-established free utility, merging looks like this:
pdftk file1.pdf file2.pdf file3.pdf cat output combined.pdfThis lists each source file in the order you want them combined, followed by the output filename for the result. It's overkill for merging two documents once, the graphical tools above are faster for that, but for automating a recurring task, combining a batch of daily reports into one file every morning, for example, a script built around a command-line tool like this can save real time over repeating the manual steps each time.
What Trips People Up
- Forgetting to check the final page order. Always open the combined file afterward and scroll through it to confirm the sequence is correct before sharing or archiving it.
- Uploading confidential documents to an unfamiliar online tool. Use a desktop tool for anything sensitive.
- Merging scanned image-based PDFs and expecting searchable text. Merging doesn't add OCR (text recognition); if your source PDFs are scanned images, the combined file will still be image-based unless you run OCR separately, which some editors like PDF-XChange include.
- Ending up with an oversized combined file. Combining several already-large PDFs can produce a large final file; if that's a problem, compressing the PDF afterward is a separate, straightforward next step.
- Not keeping the original separate files. Keep your originals until you've confirmed the merged file looks correct and complete.
What Often Comes Next
Once your document is combined, you may need to sign it electronically, or if the merged file has grown too large to email, compressing a PDF without losing quality covers that next step. For ongoing PDF editing needs beyond merging, our comparison of free PDF editors covers the fuller feature set.
Frequently Asked Questions
What's the easiest free way to combine PDF files?
A dedicated free PDF editor like PDF-XChange Editor includes a document merge feature that lets you select multiple PDFs and combine them into one file with control over page order, which is more reliable than most online-only tools for regular use.
Can I merge PDFs without installing any software?
Yes, several free online tools accept multiple PDF uploads and return a single merged file. For sensitive or confidential documents, a desktop tool avoids uploading your files to a third-party server.
Does merging PDFs reduce their quality?
No, merging simply combines the existing pages into one file without re-processing the content itself, so there's no quality loss from the merge operation. If the combined file is too large afterward, a separate compression step handles that.
Can I reorder pages while combining PDFs?
Yes, most merge tools, including PDF-XChange Editor and most free online mergers, let you drag and drop the files or individual pages into your desired order before finalizing the combined document.
Is there a way to combine PDFs using only tools already built into Windows or Mac?
On Mac, Preview can combine PDFs by dragging pages from one document's sidebar into another's. Windows doesn't have a fully native merge tool, though the Print to PDF feature can combine documents through a more manual workaround covered in this guide.
More free software picks
We track free-tier limits and free tools across dozens of categories since they change more often than you'd think.
More from the creator
Explore two other projects from the same creator.