How to Merge PDF Files for Free (Windows, Mac, iPhone & Android)

Combining several PDFs into a single document is one of the most common things people need to do with PDFs — stitching together a scanned contract, assembling a report from separate sections, or turning a pile of invoices into one file to email. The good news: you never need to pay for it. I’ve merged thousands of PDFs over the years, and below are the methods I actually reach for, depending on the device in front of me and how sensitive the files are.

What “merging” actually does

It helps to know what’s happening under the hood, because it explains a lot of the questions people have. Merging is just concatenation: the tool takes the pages of file A, then the pages of file B, and writes them into one new file in order. It does not re-encode text or re-compress images, so the result is lossless — your merged PDF looks exactly like the originals, just in one place.

That also means merging does not make a file smaller. If your combined PDF is too large to email, that’s a separate job — compression — which I cover in its own guide.

Method 1: Online (works on any device)

The fastest option when you’re not on your own computer is a web-based merge tool. The workflow is the same everywhere:

1. Open the tool in your browser.
2. Drag in the PDFs you want to combine (or pick them from your files).
3. Drag the thumbnails into the order you want.
4. Click Merge, then download the single combined PDF.

The big advantage is that it works identically on Windows, Mac, Chromebook, iPhone, and Android — no installation. The thing to watch is privacy: many online tools upload your files to a server to process them. That’s fine for a class handout, less fine for a tax return.

Method 2: On a Mac (Preview — free and offline)

macOS has a capable PDF merger built right in, and most people never realize it. Using Preview:

1. Open the first PDF in Preview.
2. Show the page thumbnails: View → Thumbnails (or press ⌥⌘2).
3. Drag a second PDF file from Finder directly into the thumbnail sidebar. Its pages drop in wherever you release them.
4. Reorder pages by dragging them in the sidebar.
5. Save with File → Export as PDF to write a fresh combined file.

Because everything happens locally, this is my default for anything I wouldn’t want on someone else’s server. One gotcha: if dragging seems to replace rather than add, make sure you’re dropping between existing thumbnails, not on top of one.

Method 3: On Windows (PDFsam Basic or PDF24)

Windows doesn’t include a built-in way to merge PDFs — the default viewer and “Microsoft Print to PDF” can’t combine multiple files. I use one of two free, offline programs:

• PDFsam Basic — open source, no upload, no nonsense. Choose Merge, add your files, drag to reorder, and run. It’s the one I recommend for privacy.
• PDF24 Creator — a free toolkit with a friendly drag-and-drop merge screen and lots of other PDF utilities bundled in.

Both run entirely on your machine, so they handle confidential files and large batches without sending anything online.

Method 4: On a phone

On a phone, a browser-based tool is the most dependable path and behaves the same on iPhone and Android. If you’d rather stay native:

• iPhone: You can import PDFs into the Books app, or build a one-tap Shortcut using the “Make PDF” action. The Files app’s “Create PDF” is designed for combining images, not existing PDFs, so don’t be surprised when it doesn’t merge them.
• Android: Most built-in file managers won’t merge PDFs, so a browser tool or a reputable free app is the way to go.

Method 5: Command line (for power users)

If you live in a terminal, this is the fastest method of all and trivially scriptable. Two reliable, free options:

# poppler-utils — order is exactly as listed
pdfunite part1.pdf part2.pdf part3.pdf merged.pdf

# qpdf — flexible page selection, also great for splitting
qpdf --empty --pages a.pdf b.pdf -- merged.pdf

Both are lossless and run offline. I keep pdfunite aliased because batch-merging a folder of files becomes a one-line loop.

Choosing the right method

Whatever you choose, the principle is the same: reorder first, merge once, and keep private files off other people’s servers. Once that clicks, combining PDFs goes from a chore to a ten-second job.