How to merge PDFs into one document
- Add your files
Select two or more PDFs. They are listed in the order they were added.
- Put them in order
Drag a file up or down the list. This is the page order of the finished document, so a paper should come before its mark scheme.
- Decide on bookmarks
Leave bookmarks switched on unless you specifically want one undifferentiated run of pages.
- Merge and check
Run the merge, then open the result and confirm the joins land where you expect - a missing insert is easiest to spot now, not the night before an exam.
Why this matters for exam and study documents
Merge a question paper with its mark scheme and you can mark your own attempt without switching windows. Merge a whole series - 2019 through 2024 - and you have a single file to work through on a tablet, offline, on a train.
What is kept, what changes, and what this will not do
Page operations copy content rather than re-rendering it, so nothing here costs quality. What changes is which pages exist and where they sit - and the numbering printed on them stops matching.
Kept
- Every page exactly as it was in its source file
- Embedded fonts, images and vector diagrams
- Internal links inside each original document
- Form fields, though field names may collide between files
Changed
- Page numbers printed on the original pages no longer match their position in the merged file
- Each document's outline is replaced by one entry per source file
- Documents can only be joined end to end; pages are not interleaved
Limits
- Up to 30 files and 50 MB in total.
- An encrypted file needs its open password before it can be merged.
Questions and answers
Does merging reduce quality?
No. The pages are copied across as they are, object for object. Nothing is re-rendered or recompressed, so a merged file looks identical to its sources and is roughly the sum of their sizes.
Can I merge a password-protected PDF?
Yes, if you supply the password that opens it. The password is used once, in memory, for that operation. If you do not have the password, the file cannot be read at all - by this site or any other.
Why is my merged file so large?
Because it contains everything from every source. If the sources are scans, the result will be heavy. Run Compress PDF afterwards and check the reported saving before you keep it.
Can I merge in a different order later?
You would merge again from the originals. Keep the source files until you are certain the combined document is right.