Merge PDF
Combine two or more PDF files into a single document, in the order you choose.
Drop in several PDFs, reorder them with the up and down buttons, and download one merged file. Useful for joining scanned pages, combining report sections, or attaching a signed page to a contract. Everything runs in your browser, so private documents never leave your device.
Your files never leave your browser — merging happens on your device.
How to use this calculator
- Click the file picker and select two or more PDF files.
- Use the up and down buttons to arrange the files in the order you want.
- Check the plan line — it shows the total page count and where each file starts.
- Click Merge PDFs and save the downloaded merged.pdf.
The formula
Pages are copied file by file in your chosen order: the start page of each file is 1 plus the total pages of every file before it.
Worked example
Merging three files of 4, 10, and 6 pages produces a single 20-page PDF. The second file starts on page 5 and the third file starts on page 15.
Frequently Asked Questions
Is there a limit to how many PDFs I can merge?
There is no fixed count limit. The practical limit is the memory of your device, because merging happens entirely in your browser. Dozens of ordinary documents merge fine; extremely large files (hundreds of megabytes) may be slow on older phones.
Are my files uploaded to a server?
No. The merge runs 100% in your browser using the pdf-lib library. Your files are never sent over the network, which makes this safe for contracts, statements, and other private documents.
Can I change the order of the files before merging?
Yes. After adding files, use the up and down arrows next to each file to set the order. The plan line shows exactly where each file starts in the merged document before you download it.
Will the merged PDF keep bookmarks and links?
Pages are copied with their content, text, and images intact. Some internal features such as bookmarks and clickable cross-document links may not survive the copy, because the pages are re-assembled into a brand-new file.
Why did one of my files fail to load?
The usual causes are a password-protected (encrypted) PDF or a damaged file. Remove the password in your PDF app first, or re-export the file, then try again.