PDF Tools
Merge PDF
Combine multiple PDF files into one.
Enter the values and review the result.
Select multiple PDF files
Max 10MB
Upload your PDFs and press Merge PDFs.
Your merged PDF and output details will appear here.
What this PDF merger does
Merge PDF combines two or more PDF files into one downloadable PDF. It is useful for joining invoice pages, forms, reports, receipts, or separate document sections.
Example: upload a cover page, a signed form, and a receipt PDF, then merge them into one file for easier sharing. File order matters because pages are added in the selected order.
This tool processes the selected PDFs in your browser, but conversion can still fail if a file is encrypted, password-protected, corrupt, unusually large, or not a valid PDF. You can also browse the PDF Tools category for related document tools.
Limitations and common mistakes
Review the merged PDF before sending it. Page size, rotation, bookmarks, forms, and metadata may not always combine exactly the way a desktop editor would.
- Do not upload fewer than two PDF files.
- Check the order before merging because the output follows the selected order.
- Avoid very large batches if your browser or device is low on memory.
- Do not use sensitive files unless you are comfortable with how this browser-based tool handles them.
Transparency note
Accuracy and limitations
Calzivo tools are built for practical estimates, conversions, and checks. Some tools use standard formulas or simplified assumptions, and results can be affected by input accuracy, rounding, units, local rules, or changing official requirements.
File and image results can vary by file structure, browser support, size, fonts, compression, and format limits. Review downloaded files before using or sharing them, and avoid sensitive files unless you understand how the tool handles them.
How to Use This Tool
Use these steps to enter the right inputs and interpret the result correctly.
Select the PDF files you want to merge.
Check that the file order matches the order you want in the final PDF.
Click 'Merge PDFs' to combine them into one file.
Download your new PDF document.
Related Tools
Other helpful tools in the PDF Tools category.
Related Guides
Background reading and explanations related to Merge PDF.
Frequently Asked Questions
Common questions about Merge PDF and how to read the result.
Is there a limit on the number of files?
You can merge up to 20 PDF files at once in the browser.
Does file order matter?
Yes. The merged PDF follows the selected file order, so check the list before creating the output.
Can password-protected PDFs be merged?
Password-protected, encrypted, corrupt, or unsupported PDFs may fail. Unlock or repair the file first if you have permission.
Will bookmarks and forms be preserved?
Pages are copied into a new PDF, but bookmarks, forms, metadata, and advanced document features may not always carry over.
Why did a large merge fail?
Very large PDFs can exceed browser or device memory limits. Try fewer files or smaller documents.
Should I review the merged PDF?
Yes. Always open the merged file and confirm page order, rotation, and readability before sharing it.