Skip to content

How to Merge PDF Files on an Android Phone

How to merge PDF files on an Android phone: preparing files, choosing page order, fixing rotation, checking the combined size and naming the result.

By Published 4 min read

Reign Creative LLC makes PDF All in One Tool No Limit, which this article links to, so we have a commercial interest in it. How we write and check articles.

AI-assisted article. Drafted with AI tools from the sources cited below and checked by automated tests and an AI editorial review. No person has reviewed it yet. How we write and check articles.

Key takeaways

  • Merging joins several PDFs into one sequential file; decide the order before you start.
  • Fix individual pages first: rotate sideways scans and remove blank pages in the source files.
  • A merged file is roughly the sum of its parts, so three files of 9, 8 and 10 MB will exceed Gmail's 25 MB attachment limit.
  • Check the result page by page, then give it a descriptive file name.
  • PDF All in One Tool No Limit merges files on Android and also rotates, removes, extracts and rearranges pages.

Merging is a PDF job that tends to turn up on a phone at awkward moments: an application that wants one file, a set of receipts for an expense claim, a scanned contract that came out as five separate files. The job itself takes seconds. Getting a clean result takes a little preparation. This guide covers both, on Android.

What merging does

Merging joins several PDFs into one sequential document. Adobe's help for its desktop Acrobat describes the same idea: preview, arrange, move or delete pages, then create a single PDF. Nothing about the pages themselves needs to change; they are placed one after another in the order you choose. That makes merging safe to repeat, but it also means any problem in a source file, such as a sideways scan, is carried into the result.

Before you merge

A minute of preparation saves re-doing the whole file:

  1. Collect the files in one place, such as your Downloads folder, so you are not hunting for them mid-task.
  2. Fix pages in the source files: rotate sideways scans and remove blank or duplicate pages.
  3. Decide the order on paper or in your head: cover letter, form, then supporting documents is one sensible sequence.
  4. Check sizes: a merged file is roughly the sum of its parts.

Merging on Android, step by step

In PDF All in One Tool No Limit, the merge tool joins several files into one document. Screens and button labels can change between app versions and look different on different Android devices, so read these as the stages rather than exact taps:

  1. Open the app and choose the merge tool.
  2. Add the files you want to combine.
  3. Arrange them in the order they should appear.
  4. Combine and save the result as a new file, keeping the originals until you have checked it.
  5. Use the page tools to rearrange, rotate, remove or extract individual pages if something is still out of place.

The same order works in any PDF app with a merge feature: add, arrange, combine, check.

A worked example: will it fit in an email?

You need to send three files: a 9 MB scanned form, an 8 MB set of scanned receipts and a 10 MB PDF of photos. Merged, they come to about 27 MB. Google's Gmail help says personal accounts have a 25 MB attachment limit, and that Gmail turns larger attachments into Google Drive links instead. To send the merged file as a normal attachment, compress it first, or compress the two scanned files before merging. How to compress a PDF explains the trade-offs.

Check the result

Before sending, scroll through the merged PDF once:

  • Order: are the sections where you intended?
  • Orientation: are any pages sideways or upside down?
  • Completeness: is the page count the sum of the originals?
  • Duplicates or blanks: did a blank page sneak in from a scan?

Then rename the file to something descriptive, such as "2026-10 expense claim receipts.pdf". The app's PDF manager lets you review, organise and rename files before sharing.

Mixed sources, mixed page sizes

Files from different places may not match. A form from a US website may be letter size, a document from Europe A4, and a phone scan whatever shape the camera captured. Where a merge keeps each page's own size, the combined file may change shape from page to page. That is not an error, but if the recipient expects a uniform document, scan or export everything at one size before merging. The same applies to orientation: a landscape spreadsheet page among portrait pages is fine, as long as it is the right way up.

Keep a clean record

A few habits make merged files easier to live with later:

  • Keep the originals in a folder until the merged version has been accepted, so you can rebuild it if something is wrong.
  • Use dated, descriptive names, starting with the year and month, so files sort in order.
  • Save a new version rather than overwriting when you correct a merged file, for example "v2", and delete the old one once the new one is sent.

Check what you are sharing

Merging makes it easy to send more than you meant to. Before sharing, make sure the file does not contain pages from another document that were in the same folder, an earlier draft or a page with personal details the recipient does not need. Removing a page takes seconds with the page tools; recalling an email does not.

When to split instead

Sometimes the right answer is the opposite: one long PDF that needs to go to different people. How to split a PDF covers extracting pages and dividing files, and scanning documents to PDF covers getting clean pages in the first place.

PDF All in One Tool No Limit is one of our video and utility apps; its guide maps every common PDF job to its tool.

Good to know

Frequently asked questions

How do you merge PDF files on an Android phone?
Open a PDF app with a merge tool, add the files you want to combine, arrange them in the order you want, and save the result as a new PDF. Check the combined file page by page before sending it.
How do I change the page order when combining PDFs?
Arrange the files in the merge screen before combining, then use a page tool to rearrange individual pages inside the merged file if needed. Adobe's Acrobat help, for example, describes previewing, arranging, moving or deleting pages before creating one sequential PDF.
Why is my merged PDF so big?
Because merging keeps the contents of every file, so the result is roughly the sum of the originals. Image-heavy scans are the usual cause; compress the merged file, or the large inputs, before sending.
Does merging change the quality of the pages?
Merging itself only combines pages; it does not need to re-encode them. Quality changes come from compressing or converting, so compress as a separate, deliberate step and check the result.

Sources

  1. Combine files into one PDF in Acrobat (opens in a new tab)Adobe — accessed
  2. Send attachments with your Gmail message (opens in a new tab)Google Gmail Help — accessed
  3. PDF (opens in a new tab)Wikipedia — accessed

About the author

— The independent app studio that builds the apps covered on this site and publishes every article here. On Google Play it publishes as Reign Collective Apps.

We use AI tools to help research, draft and edit our articles. Each article lists the sources its factual claims rely on, and details about our apps come from their live Google Play listings. No article on this site has been reviewed by an independent expert unless the reviewer is named on it.

No person at Reign Creative LLC has read this article in full. It was published after automated checks and an AI editorial review, which are described in our editorial policy and are not the same as a person reading every sentence.

Spotted an error? Tell us — how corrections are handled is set out in our editorial policy.

Keep reading