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How to merge PDF files into one document

Last updated: 1 November 2026

To merge PDF files, open Merge PDF, add your PDFs, drag them into the order you want, click “Merge PDF” and download the single file. Your browser combines the files on your own device, so nothing is uploaded, and you don't need an account.

This guide is for anyone who needs to send several documents as one, such as a job application with a CV and certificates, monthly invoices, scanned pages or the chapters of a report. It also shows how to shrink the merged file and how to move individual pages.

Open Merge PDF

Step by step

  1. Select your PDFs. Open Merge PDF and click “Select PDF files”, or drag and drop two or more PDFs onto the page. You can add more files at any time.
  2. Put the files in order. Drag the files into the order you want, or use the arrow buttons. On a phone, drag each card by its handle. You can also sort the files by name with one click.
  3. Choose your options. By default every file gets a bookmark and keeps its own bookmarks. You can choose “Keep existing only” or “None” instead. If you plan to print double-sided, tick “Add a blank page after files with an odd number of pages”.
  4. Merge the files. Click “Merge PDF”. Your browser combines the files on your device, and nothing is uploaded.
  5. Download the merged PDF. Click “Download” to save the single PDF to your device.
  6. Check the result. Open the merged file and scroll through it to confirm the page order. If the file is too large to send, continue with Compress PDF.

Tips for job applications and upload portals

Many application forms and portals accept only one file, so merging is often the simplest way to send everything together. These habits help you avoid mistakes.

  • Send one file. Put the cover letter first, then the CV, then certificates or references, unless the portal asks for a different order.
  • Name your files before you add them. If you start file names with numbers, such as 01-cover-letter and 02-cv, sorting by name puts them in the right order with one click.
  • Give the merged file a clear name. Before uploading, rename it on your device so the reader knows whose document it is and what it contains.
  • Check the page order before you send it. Open the downloaded PDF and look at every page. A file placed in the wrong spot is easy to miss.
  • Watch the file size. If the portal rejects the file as too big, make it smaller with Compress PDF as described below.

You can merge PDFs with different page formats. A4 scans, US Letter forms and landscape slides all end up in one document, and each page stays exactly as it was.

How to make the merged PDF smaller

Merging copies pages as they are and does not re-compress text or images, so the merged file is roughly as large as all your files together. To shrink it, use Compress PDF.

  1. Select the merged PDF in Compress PDF.
  2. Start with “Recommended”. Choose “Extreme compression” if the file is still too big, or “Less compression” to keep images sharper.
  3. Optionally tick “Convert to grayscale”, or set the image resolution and JPEG quality under “Advanced settings”.
  4. Click “Compress PDF”, check the new size and click “Download”.

How much smaller the file gets depends on what is inside it. Scans and photo-heavy PDFs usually shrink a lot, while text-only PDFs may hardly change. You never get a file that is bigger than the original.

When to use Organize instead

Merge PDF joins whole files. If you need to move single pages, for example to put an appendix at the end or fix a double-sided scan, use Organize PDF. It shows every page as a thumbnail, and you can drag pages into place, rotate them, remove them or insert blank pages.

You can also click “Add PDF” in Organize PDF to mix pages from several files. If you only reorder and rotate pages, bookmarks, form fields and links keep working. If you remove, insert or add pages, the bookmarks are not carried over.

Tools used in this guide

Frequently asked questions

Are my files uploaded when I merge them?

No. Your own browser merges the files, and they are never uploaded to a server. PDF4U pages are also blocked from connecting to other websites, so your files can't be sent anywhere by mistake.

How many PDFs can I merge at once?

There is no fixed number. You can merge dozens of files or very large PDFs, and the only limit is your device's memory. On phones, very large files of hundreds of megabytes may be slower.

Can I change the order after adding the files?

Yes. Before you click “Merge PDF”, drag the files, use the arrow buttons or sort them by name. After merging, you can fine-tune individual pages with Organize PDF.

Will the merged PDF keep the original quality and bookmarks?

Yes. Pages are copied without re-compressing text or images. Each file's bookmarks are kept and nested under one new bookmark per file, unless you choose “Keep existing only” or “None”.

Can I merge PDFs on my phone?

Yes. PDF4U works in modern browsers on Android, iPhone and iPad, as well as on Windows, Mac and Linux. To reorder files on a phone, drag each card by its handle.

Can I merge password-protected PDFs?

Remove the password from each file first. You need to know the password to do this. Then merge the unlocked files as usual.

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