How to combine PDFs on a phone
You have a few PDFs on your phone and need to send them as one. Here are the ways to do it there, without a computer, and what to expect from the result.
Reviewed by Victor Yuki Matusita on . First published . First version, with the measurements of November 2, 2026.
Forms, receipts, a signed page and a scan of an ID can arrive as separate PDFs, and the place you need to send them takes a single file. On a computer there are plenty of ways to join them. On a phone there are fewer, and they depend on the phone.
This guide covers the way Apple documents for the iPhone, the way that works in a browser on any phone, and what we measured when we merged five pairs of our test PDFs.
Combine your PDFs here
Choose two or more PDFs from your phone, drag them into the order you want and tap the button. They are joined in this browser tab, on the phone itself, and nothing is uploaded.
Drop PDFs here
or paste with Ctrl+V · PDF files, as many as you likePDF files, as many as you like
On an iPhone, with Preview
Apple’s iPhone User Guide describes how to add pages to a PDF in the Preview app: open the PDF, touch and hold a page thumbnail, then tap Insert from File to bring in another PDF or an image. To change the order, touch and hold a thumbnail and drag it above or below another one.
This works well for adding one file to another. For several files, you repeat the insert for each one, and the result is the PDF you started from with the new pages added.
On an Android phone
Google’s help for the Drive app describes scanning paper into a PDF: you scan a page, tap Add to scan another, and save the result as a PDF. That is a good way to turn several sheets of paper into one file, but it makes a new PDF from the camera. It does not join PDFs you already have on the phone.
For files that are already PDFs, the browser is the simplest place to do it on Android, with the tool on this page.
On any phone, in the browser
Merge PDF on this page runs in the browser of the phone, so it works the same on an iPhone and on an Android phone. Tap to choose the files, from the Files app on an iPhone or from your downloads on Android, put them in order and tap the button. The merged PDF downloads like any other file.
The files are not uploaded to a server: the phone does the work, so private documents stay on it.
What the merged file weighs
We merged 5 pairs of our test PDFs and compared the merged file with the two files it came from. The merged file was never bigger than the two together, and it came out smaller in 5 of the 5 pairs, by very different amounts.
Our PDF of photos with the scanned book page, and the scanned NASA report with that same page, came out just under their combined size: 3,084,947 bytes against 3,085,804 bytes, and 3,773,176 bytes against 3,783,075 bytes. A PDF has some structure around its pages, and the merged file needs that structure once instead of twice; the pictures stay as they were. The lecture notes with the IRS form came out 1% smaller.
When the merged file is clearly smaller
The scanned book page with the IRS form came out 23% smaller than the two files together. The form carries a second description of itself, in a format called XFA, that only some programs read, and Merge PDF leaves it out; the result tells you so next to the file. The form fields themselves are kept, so the form can still be filled in. Our PDF with pages of mixed sizes and our PDF with links and actions came out 18% smaller together: our test script wrote both without packing their structure, and the merged file is written packed.
Nothing else is dropped on purpose. Bookmarks and links come along, and a field whose name already exists in another file gets a number added so both keep working.
Before you merge
Put the files in the order the reader should see them, and remove the pages that are not needed first: a merged PDF is easier to check than to fix. A PDF that asks for a password has to be saved without it before it can be merged, which Unlock PDF does; Merge PDF tells you which file is locked.
If the merged file is too big to send, compress it afterwards. Merging does not make files lighter by itself, apart from the savings above.
Sending the merged PDF
A personal Gmail account sends attachments up to 25 MB; above that, Google turns the attachment into a Drive link. If your merged PDF is near the limit, Compress PDF may bring it under. In the measurements of our guide to large PDFs, it made a PDF of photos and a scanned color page much lighter, and a black and white scan only a little; that guide has each mode on each file.
Check the merged file before you send it: open it, scroll through every page and make sure the order is right. It takes a minute, and it is much easier than explaining a missing page later.
What we measured
We merged five pairs made from seven of our test PDFs, in the order shown. Change is the merged file against the two files together.
| Files | Together | Merged | Change |
|---|---|---|---|
| Scanned book page in color + IRS Form 1040 | 314 KB | 242 KB | −23% |
| PDF made of photos + Scanned book page in color | 3.1 MB | 3.1 MB | 0% |
| Lecture notes with embedded fonts + IRS Form 1040 | 5.5 MB | 5.4 MB | −1% |
| Scanned NASA report, black and white + Scanned book page in color | 3.8 MB | 3.8 MB | 0% |
| PDF with pages of mixed sizes + PDF with links and actions | 10.4 KB | 8.6 KB | −18% |
Measured on November 2, 2026 in Node with the engine of this site, which gives the same bytes as the browser, on pairs of the PDFs of our tests.
Sources
Related tools and guides
Split PDF
Cut a PDF into parts: every page, ranges or picked pages.
Compress PDF
Make a PDF smaller, with or without touching its images.
Reorder PDF pages
Change the order of the pages of a PDF.
Image to PDF
Put your images in one PDF, one image per page.
How to split a PDF, and why the parts can weigh more
Why the parts of a PDF can add up to more than the whole, and when they do not.