How to merge PDF files

Merging joins several PDFs end to end into one document. It is one of the few PDF operations that costs nothing at all — pages are copied across as objects rather than re-rendered.

1. 01

   Add your files

   Drop in two or more PDFs. Each one shows its page count so you can check nothing is missing.

2. 02

   Put them in order

   Use the up and down controls. The order here is the order in the finished document.

3. 03

   Merge and download

   Export to combine them into a single file.

What survives, and what does not

Text, fonts, images, vector drawings and page rotation all come across exactly as they were. What can break is anything that referred to a page number: an internal link or a table of contents built for the original document now points somewhere else.

Size

The merged file is roughly the sum of its parts, because nothing is recompressed. If the result is too large for its destination, remove pages you do not need rather than compressing — compression here rasterises pages and costs you the text.

Mistakes worth avoiding

• Merging first and then discovering half the pages were not needed. Trim each file first.
• Assuming a table of contents still works afterwards.
• Merging scans and text documents and then compressing the whole thing — the text pages pay the price for the scans.