Merge PDF: Combine Files in the Right Order

The Merge PDF tool combines two or more PDFs into a single document in the order you arrange them. It accepts up to 20 files, 500 pages in total, with a size limit per file shown on the page. Page size, orientation and rotation are kept, so a landscape chart stays landscape after merging.

Merging is simple until the order is wrong. Scanned attachments, signed pages and appendices often need to sit in a specific sequence, and a file picked in the wrong order produces a document that is technically valid and practically useless. The tool lets you reorder before merging, and it keeps the order you see.

#What the tool keeps and what it drops

The merge imports each page into a new document. That preserves how pages look, but it does not preserve the interactive layer around them. If a source PDF has fillable fields, those fields will not be fillable in the merged file. If it has bookmarks, the merged document will not have a navigable outline for those sections.

#How to merge PDFs

1. Open the Merge PDF tool.
2. Choose at least two PDFs. You can select several at once or add them in batches.
3. Check the list. Each file shows its name and size, and a running total appears below.
4. Reorder with the up and down arrows. The top file becomes the first pages of the output.
5. Remove anything you added by mistake with the × button, or clear the list and start again.
6. Press Run.
7. Download merged-YYYYMMDD-HHMMSS.pdf and check the page order.

The merge runs on the server. Temporary copies are deleted after processing, and download links expire.

If your browser cannot rewrite the file selection, the arrows are disabled and a note says the files will merge in the order you picked them. That is a browser limitation, not a silent reorder: the tool tells you rather than promising an order it cannot honour.

#Limits that matter

• 2 to 20 files. A single PDF does not need merging; use the editor or converter instead. More than 20 files should be merged in batches.
• 500 pages combined. The limit exists because every imported page is held in memory. A 600-page merge is more likely to fail than to succeed, so split the job.
• Size per file. The limit is shown on the tool page. A large scanned PDF may hit it even if the page count is low.
• No encryption. Password-protected PDFs cannot be imported. Remove the password first.

#Common problems and fixes

The pages are in the wrong order. The list order is the output order. Use the arrows to move files, or remove and re-add them in the right sequence. If the arrows are disabled, your browser could not reorder the selection; add the files one at a time in the intended order.

A file is rejected as invalid. It may be encrypted, damaged, or not actually a PDF despite the extension. Open it in a reader to confirm, remove any password, and try again.

The merge fails on a large job. Reduce the number of files or split the documents first. The 500-page cap is a hard limit, and a job near it with large pages can still be slow.

Form fields no longer work. That is expected. Merging rebuilds pages and does not carry interactive fields. If the forms must remain usable, keep them in separate files or rebuild the form after merging.

Bookmarks disappeared. Outlines are not transferred. If navigation matters, add bookmarks in a PDF editor after merging, or keep the sections as separate files.

A page is rotated differently from the rest. Rotation is preserved from the source. Fix the rotation in the source PDF before merging, or rotate the page afterwards.

The output is much larger than the inputs. Importing pages can duplicate shared resources such as fonts and images. Compression after merging usually helps; for image-heavy files, optimise the images first.

The download link expired. Links are temporary. Re-run the merge and download promptly.

#Planning the order before you merge

The most common merge mistakes are ordering mistakes. A useful checklist:

1. Write the intended order down first. File names are often unhelpful: scan001.pdf, document (3).pdf, final-final.pdf.
2. Put the cover first, then the body, then appendices. If the document has a table of contents, the page numbers must match the merged result, not the individual files.
3. Keep signed pages adjacent to what they sign. A signature page separated from its contract by an appendix is a problem.
4. Merge related documents separately if they have different audiences. One 300-page file is harder to share than three focused ones.
5. Check page numbers after merging. If each source had its own numbering, the merged file will restart or jump. Add continuous numbering afterwards if needed.

#Merge, split or edit?

These tools solve different problems:

• Merge when several documents belong in one file.
• Split PDF when one document contains several that should be separate, or when you only need a page range.
• PDF editor when a page needs a small text correction before or after merging.
• PDF to Word when the merged content needs substantial editing.

A practical sequence for assembling a report: convert or edit each section first, export each to PDF, merge in order, then check the result. Editing after merging works too, but fixing a page in a 200-page file is slower than fixing it in a 10-page source.

#Quality checks after merging

• Page count. The result reports the combined count. Compare it with the sum of the inputs; a missing page usually means one source failed to import.
• First and last page of each section. These are where order errors show up.
• Page size and orientation. Flick through and look for a landscape page that should be portrait, or a page that is unexpectedly small.
• Text selection. Try selecting text on a few pages. If a page is a scan, it will not select; that is a property of the source, not the merge.
• File size. Large merges can be heavy. Compress images or the final PDF if it needs to be emailed.

#Privacy

The PDFs are uploaded to the server and merged there. Temporary copies are deleted afterwards, and download links expire. That is fine for ordinary documents, but merging signed contracts, medical records or identity documents means sending them to a third-party service. Decide whether that is acceptable before uploading.

#Frequently asked questions

#Bottom line

Merging is only as good as the order you choose. Arrange the files, check the running page total, and verify the first and last page of each section after downloading. Start with the Merge PDF tool, use Split PDF when one file needs to become several, and fix content with the PDF editor before combining.