How to merge PDF files: combine PDFs on any device

Before you start

A few minutes of preparation saves you from merging twice. PDF is a page-based format: a PDF file is a sequence of fixed pages, with their text, fonts and images described inside the file (the Library of Congress gives a clear technical overview of the PDF format family). Merging simply places the pages of several files one after another in a new file, so the main things to get right are the order and the files themselves.

• Collect the files in one folder. It’s much easier to select them together, especially on a phone.
• Name them in order. Prefixes such as 01-cover.pdf, 02-report.pdf and 03-appendix.pdf make the order obvious and keep it when files are sorted by name.
• Check for passwords. If a PDF asks for a password when you open it, you’ll need that password to unlock it first with Unlock PDF.
• Know your size limit. Email services and upload portals often limit attachment size. If yours does, plan to compress the result.
• Convert anything that isn’t a PDF. Photos and scans saved as JPG or PNG can be turned into PDF pages with Images to PDF; Word files with Word to PDF.

Merge PDFs online (any device)

An online tool is the quickest method on almost any device, because everything happens in the web browser you already have. Here’s how it works with ToolsMotive:

1. Open Merge PDF.
2. Drop your PDF files onto the page, or choose Choose PDF files and select them. On a phone, you can pick files from your device or from cloud storage.
3. Arrange the files: drag them up or down, or use the arrow buttons. Each file shows its first page and page count.
4. Optionally type a file name and, if you need one, a size target.
5. Choose Merge PDFs. The tool merges the files, re-opens the result and checks the page count, then shows the file name, size and number of pages.
6. Download the merged PDF.

You can also describe what you want instead of clicking through settings. Type a request such as “merge these and put the cover page first” and ToolsMotive sets up the order for you, then shows the plan so you can adjust it before anything runs. Merge PDF runs in your browser: your files are merged on your own device and are not uploaded to our servers to be processed. If Library saving is on, a copy is kept in your private Library.

Merge PDFs on a Mac with Preview

Every Mac includes Preview, which can combine PDFs without any extra software. Apple documents the method in its Preview user guide (Combine PDFs in Preview on Mac). In short:

1. Open the PDFs you want to combine in Preview.
2. In each document, choose View > Thumbnails to show the page thumbnails in the sidebar.
3. Drag the thumbnails you want from one document’s sidebar into the other’s. To select pages that aren’t next to each other, Command-click each one.
4. To add a whole PDF, drag its icon from the Finder into the sidebar of the open document.

Important: Apple notes that changes save automatically, so if you want to keep the original files unchanged, choose File > Duplicate for each PDF before combining them.

Preview is ideal for moving a few pages between two documents. For many files, a fixed file order, a size target or a page-count check, the online method above is usually faster.

Merge PDFs on Windows

Windows doesn’t include a built-in tool for combining PDF files: File Explorer and the browser’s PDF viewer can open PDFs, but not join them. The no-install option is an online merge tool, which works in Microsoft Edge, Chrome, Firefox or any modern browser:

1. Open Merge PDF in your browser.
2. In File Explorer, select your PDFs (hold Ctrl and click each one) and drag them onto the page.
3. Check the order, then choose Merge PDFs and download the result. It usually goes to your Downloads folder.

If you merge PDFs regularly, sign in and keep the results in your Library, so you can reuse them later without searching through your Downloads folder.

Merge PDFs on iPhone and iPad

On iPhone and iPad, the method that works the same on every iOS version is to use the browser:

1. Open Merge PDF in Safari (or any browser).
2. Tap Choose PDF files, then choose Browse to pick PDFs from the Files app, iCloud Drive or another connected storage service.
3. Arrange the files, tap Merge PDFs, then tap Download.
4. Open the download from Safari’s downloads list, or find it in the Files app under Downloads, and share or save it.

Apple’s apps change their menus between iOS versions, and Apple’s iPhone User Guide doesn’t describe a dedicated merge feature in the Files app, so the browser method is the most reliable way to get the same result every time.

Merge PDFs on Android and Chromebook

Android phones and Chromebooks work the same way through the browser:

1. Open Merge PDF in Chrome (or another browser).
2. Tap Choose PDF files and select the files from your device storage or Google Drive.
3. Order the files, merge, and download. The file is saved to the Downloads folder, where you can open or share it.

Because nothing needs installing, this also works on shared or work devices where you can’t add apps.

Merging scanned documents

Scanners and phone scanning apps often create one PDF per page. Merging puts them back together as one document, but keep two things in mind:

• Scanned pages are pictures of text. After merging, you can’t search or copy the text until you run OCR PDF, which adds a searchable text layer.
• Scans are large. A few dozen scanned pages can easily exceed an email limit. Compress after merging, or set a size target before you merge.

With ToolsMotive you can do all of it in one request, for example: “Combine these scans into one PDF, make the text searchable and keep it under 10 MB.” Each step is shown as it runs.

Keeping the merged file small

A merged PDF is roughly as large as all the original files added together, because merging copies pages without changing them. That’s good for quality (text stays sharp and selectable) but it can be a problem for sending. Three ways to stay under a limit:

1. Set a size target in Merge PDF. If the result is too big, a compression step is added automatically, and you’re told plainly if the target can’t be reached without a visible loss of quality.
2. Compress afterwards with Compress PDF, choosing a stronger setting only if you need it.
3. Leave out what you don’t need. Remove blank or duplicate pages with Delete PDF pages before sending.

For a deeper look at what makes PDFs large and how to shrink them safely, read how to reduce PDF size without losing quality.

Worked example: one PDF from a month of invoices

Here’s a real test we ran in the ToolsMotive preview with three sample files: a one-page cover sheet (Cover-page.pdf), a two-page invoice (Invoice-1041.pdf) and a three-page invoice (Invoice-1042.pdf).

1. We dropped all three files at once. Each file was checked and its pages counted: 1, 2 and 3 pages.
2. We typed “put the cover page first” and moved Invoice-1042 above Invoice-1041 with its arrow button.
3. We named the file October-invoices and chose Merge PDFs.
4. The result had 6 pages, and the check confirmed 6 of 6 pages. We downloaded the file and opened it separately in another PDF program: 6 pages, in the order we chose.

The whole task took under a minute, and the merged file appeared in the Library, ready to compress, number or send.

Common mistakes to avoid

• Merging in the wrong order. Check the order in the list before merging; it’s quicker than reorganising pages afterwards.
• Overwriting originals on a Mac. Preview saves automatically, so duplicate your files first.
• Forgetting the size limit. Check the file size shown after merging before you attach it to an email.
• Merging forms with identical field names. If two PDFs contain form fields with the same names, their values can become linked. Fill in or flatten forms first.
• Expecting bookmarks to carry over. Many merge tools don’t keep each file’s bookmarks. Add an outline afterwards with PDF bookmarks if readers need one.