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How to merge PDF files into one document
Combine reports, scans and invoices into one tidy PDF
When merging is useful
Most people merge PDFs when a form or application asks for a single attachment but the paperwork exists in pieces: a scanned ID, a bank statement, a signed cover letter and a typed CV. Accountants merge monthly invoices into one file for a client. Students combine chapters or lecture notes. Merging keeps related pages together, makes email attachments easier to manage and avoids the risk that a recipient opens only half of your documents.
Step by step
- Open the Merge PDF tool and choose all the files you want to combine. You can drag them in or use the file picker.
- Check the list that appears. Files are joined from top to bottom, so use the up and down arrows to put them in the order the reader should see them.
- Remove any file you added by mistake with the cross button.
- Press Merge PDFs. When the result is ready, download merged.pdf.
Tips for a clean result
- Rename files with numbers (01-cover, 02-statement) before you add them. It makes the order obvious.
- If one source has pages in the wrong orientation, rotate it first with the Rotate PDF tool, then merge.
- Merging does not reduce file size. If the combined file is too big to email, run it through Compress PDF afterwards. Note that compression turns pages into images, so do it last.
- Password-protected files should be unlocked first. Use Unlock PDF only on files you own or are allowed to open.
Common questions
Is there a page or file limit? There is no limit set by FirePDF. Because your own device does the work, the practical limit is your browser memory. Very large scans may take longer or fail on older phones.
Will bookmarks and form fields survive? Page content is preserved. Document-level extras such as bookmarks may not carry over, so check the output if you rely on them.
Everything described here runs inside your browser tab. Your files are not uploaded to a server, which you can confirm by turning off your internet connection after the page has loaded and running the tool again.
More help: all FirePDF guides.