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5 things to check before you merge PDFs into one file
Short answer
- Before merging, write down the order the recipient asked for and arrange the files in that order.
- Digitally signed certificates can fail signature checks once they are merged into a new file, so send those separately when the original is required.
- If the merged file is too large, compress it afterwards; add page numbers only once the order is final.
1. Follow the order the recipient asked for
Job applications, scholarship forms and insurance claims that ask for a single file usually list the documents in a set order. Copy that list somewhere you can see it, and prefix your file names with 01_, 02_ and so on so they are easy to sort. In Merge PDF the files are joined from top to bottom: drag a row to move it, or use the up and down arrow buttons on each row, which are easier on a phone.
2. Keep signed certificates separate
Some official documents, such as certificates issued by a government portal or a university, are PDFs with a digital signature that lets the recipient confirm the file has not been changed. Merging that PDF with others creates a new file, and the signature may no longer validate. If the recipient asks for the original electronic document, attach it on its own instead of merging it.
3. Check the size of the merged file
A merged PDF is roughly the sum of the files that went into it. If some of them are scans or phone photos, the result can easily pass an upload limit. Try Compress PDF on the merged file; the guide on reducing PDF size for upload limits explains which setting to try first.
4. Look for sideways pages
A landscape table or a scan taken the wrong way round will show up as a sideways page in the middle of the merged file. Check each source file before merging, or turn just the affected pages afterwards with Rotate PDF.
5. Add page numbers last
If the recipient needs page numbers, add them only after the order and the page count are final, using PDF Page Numbers. You can show the total as well, as in “3 / 12”, and leave the cover page unnumbered by setting a page range. The guide on adding page numbers to a PDF walks through it.
Common questions
Does merging reduce quality?
No. FileLivo’s Merge PDF copies the original pages into a new file without re-rendering them, so text and images look the same as before. The result is saved as merged.pdf.
Can I include JPG photos?
Turn the photos into a PDF first with Image to PDF, then merge that PDF with the others. The guide on combining photos into one PDF covers page size and layout.
What if one of the PDFs is password protected?
A locked PDF cannot be opened for merging. Open it with its password in your PDF reader, save an unlocked copy, and merge that copy instead.