How to merge PDF files and get the pages in the right order

Combining PDFs sounds trivial until the pages come out in the wrong order, the file is too large to send, or one document turns out to be password-protected. A little preparation avoids all three.

Before you merge

• Name files in order. If you prefix them with numbers, such as 01-cover.pdf and 02-report.pdf, a single “Sort by name” puts them in the right order. Use two digits so that 10 sorts after 09, not after 1.
• Remove what you do not need first. Merging copies every page. If a file has blank or duplicate pages, extract the ones you need beforehand, or after merging.
• Check for passwords. A PDF that asks for a password when you open it must be unlocked with that password before its pages can be copied.

Merging step by step

1. Open Merge PDF and add all the files at once, or a few at a time.
2. Check the list: the number on the left is each file’s position in the result, and the page count is shown under each name.
3. Fix the order with the arrow buttons, by dragging, or with “Sort by name”.
4. Give the result a name and merge. Then download it or pass it to another tool.

Getting individual pages in order

Merging works at the level of whole files. When you need finer control, for example the signature page of one document placed after page 3 of another, merge first and then use Extract PDF Pages on the result. Type the new order, such as 1-3, 12, 4-11, and you get a document with exactly those pages in exactly that order.

If the merged file is too big

A merged PDF is roughly as large as all the inputs together, because nothing is re-compressed. Email services commonly limit attachments to about 20 to 25 MB. If you are over that, compress the merged file: scanned pages and photos usually shrink a lot, text-only documents much less. For files that stay large, sending a download link instead of an attachment avoids the limit completely.

What does not survive a merge

Pages, text, images and web links on the pages are kept. Bookmarks (the outline panel some readers show) and document-wide form data are not carried over, because each source file defines them for itself. If you rely on bookmarks, add them again in a desktop PDF editor after merging.