How do I merge PDF files into one?
Add two or more PDFs above, arrange them with the ↑ ↓ buttons, and click Merge PDF. The tool will merge PDF files into a single document in the order you set, keeping the original quality, text and links. If a portal has a size limit, turn on Limit file size and the merged file is compressed to your KB target in the same step. Files never leave your computer or phone.
Why combine PDFs?
Portals often allow only one upload box per section, so you need to combine PDFs before submitting.
- "Upload all documents as one PDF" instructions on job, admission and scholarship portals.
- Marksheets of all semesters in one file for verification.
- Application form + annexures + certificates submitted together.
- Invoices and receipts for accounts or reimbursements.
- Chapters or scanned pages that were saved as separate files.
Merge only, or merge and compress?
| Setting | What happens | Best for |
|---|---|---|
| Merge only (default) | Pages are copied exactly. No quality change. | Email, printing, archives |
| Merge + limit size | Merged file is compressed to your KB limit if it is bigger | Portals with limits like 200KB, 500KB or 1MB |
| Merge + limit + grayscale | Smallest file for text documents | Large bundles of black-and-white scans |
Steps to merge PDFs
- 1Add your PDFs
Select several files at once or add them one by one. Page counts appear next to each file.
- 2Set the order
The first file in the list becomes the first pages of the merged PDF.
- 3Optional: limit file size
Turn it on and choose a KB value if the portal has a cap.
- 4Merge and download
The result shows the total pages and final size.
Common problems and fixes
- "Password-protected" error: open the PDF with its password, choose Print → Save as PDF to make an unlocked copy, then merge.
- Some pages are photos, not PDFs: convert them first with Convert Images to PDF, then merge.
- Merged file too big: turn on the KB limit, or compress afterwards with Compress PDF to 500KB.
- Wrong page order: reorder the files and merge again. It takes only seconds.
- Mixed page sizes: if the portal needs all A4 pages, run the result through Resize PDF for Application Form.
How many files can I merge?
There is no fixed limit. Ten or twenty normal documents merge in a few seconds. Very large scans (hundreds of pages) depend on your device memory. If your browser slows down, merge in two batches and then merge the two results.
Private and free
Most popular PDF websites upload your documents to their servers. Some limit free merges or ask you to sign in. This tool merges locally using the open-source pdf-lib library. That makes it safe for personal and official papers, and it works without any account. For background on the format, see PDF (Wikipedia).
Frequently Asked Questions
How do I merge PDF files?
Add your PDFs on PhotoKB Merge PDF Files, set the order and click Merge PDF. Download the combined file.
Does merging reduce quality?
No. Pages are copied exactly unless you turn on the file size limit.
Can I change the order of PDFs?
Yes. Use ↑ and ↓ to move files before merging.
Can I merge and compress at the same time?
Yes. Turn on Limit file size and choose a KB value.
Why does a file show a password error?
Password-protected PDFs must be unlocked first. Open it and use Print → Save as PDF.
Is there a limit on files?
No fixed limit. Very large sets depend on your device memory.
About this tool
Built and maintained by the PhotoKB Editorial Team. We test every tool with real phone photos, scans and PDFs before each update. Exam and portal values are based on public official notifications. PhotoKB is not linked to any exam body, so always confirm current rules on the official website. Last updated: 8 November 2026.