Merge PDF files

Start with the right versions of your files

When a form or email needs one attachment, merging can turn a main document and its supporting material into a single PDF. Before adding files, open them and check that each is the version you intend to send.

A filename alone may not reveal that a document is outdated or contains an extra cover page. Look at the first and last pages, remove any duplicate documents from your selection, and decide which file should come first. The merger does not choose the newest version or remove duplicate pages.

Keep the source files. Merging produces a separate PDF, and a combined copy is not a substitute for originals whose signatures, forms, or other document features you need to preserve.

Arrange whole documents in reading order

Use Choose PDF files or drag PDFs into the file area. Add at least two files and wait for them to finish loading. The list shows each file’s page count so you can check what has been added.

Drag files into order, or use Move up and Move down. The merger reads this list from top to bottom: every page of the first PDF, followed by every page of the second, and so on.

Select Merge PDF files, then Download PDF when the result is ready. The download is named merged.pdf. If you add, remove, or reorder files afterward, merge again to create a result that matches the new list.

Moving a file moves all of its pages together. If you need only part of a document, use the PDF splitter to extract those pages first, then add the saved PDF here. To insert pages in the middle of another document, split that document into the pieces you need before merging them in order.

Try a two-page document with a three-page attachment

You can use these sample PDFs to check how file order becomes page order. They contain page labels, so the join is easy to inspect.

Save the two-page application sample and the three-page attachment sample, then add both to the tool. Put the application first and the attachment second, and merge them.

The result should have five pages in the order below. Open the downloaded file and check the transition from page 2 to page 3: Application 2 should be followed by Attachment 1.

If you reverse the file order, the three attachment pages will come first. A five-page total alone cannot tell you whether the order is correct; it is the page labels at the join that confirm it.

How the pages appear in the combined file

The merger copies the existing PDF pages into a new document without first turning them into images. It does not reflow paragraphs, make small text larger, or improve a blurry scan.

Page sizes and orientations are not standardized during merging. A US Letter page and an A4 page can remain different sizes in the same file, and portrait and landscape pages can appear together. If the recipient requires one paper size or orientation, prepare the source documents accordingly.

Page numbers printed on the pages also stay as they are. For example, a source page printed with “1” may become page 3 in the combined PDF. This tool does not add new page numbers or rewrite a table of contents.

Check the downloaded file in a PDF viewer before sending it. Selectable text can remain selectable when it exists in the source, but merging does not add OCR to a scanned image or guarantee that every document feature will carry over.

Check file limits and unsupported PDF features

All of the limits below apply at the same time. A batch under 50 MiB can still be rejected if it contains more than 200 pages, and each individual PDF must fit within the per-file limit.

Password-protected, damaged, and empty PDFs are not supported. The tool also rejects documents containing forms, annotations, bookmarks, attachments, layers, accessibility tags, or other unsupported document features. Annotations can include links as well as visible comments, so a PDF that looks like ordinary text may still be rejected.

If a file is rejected, return to the application that created it and check whether a suitable plain document copy is available. Do not discard signatures, accessibility features, or interactive content that the recipient needs just to make a file merge. Use a workflow designed to preserve those features instead.

Only PDF files can be added. Word documents and photos need to be converted to PDF elsewhere first. This tool does not unlock, repair, or convert them.

Check the downloaded PDF before you send it

Open merged.pdf and compare its page count with the total shown in the tool. Then check the first page, the joins between documents, and the final page. This helps catch the wrong file order or an unwanted extra page that a total alone would miss.

Look at small text, scans, and rotated pages at a readable zoom level. If information was missing or illegible in a source file, merging will not fix it. Return to the source document and make the correction there.

Finally, check the receiving site’s file-size limit. The merger’s 50 MiB input limit is not a promise that the downloaded PDF will fit a smaller upload allowance. Keep the original documents and give the combined file a name that makes sense to its recipient.

Questions about merging PDFs

Further reading

• pdf-lib: copying pages between PDF documentsDocuments the page-copying operation used by the merger. This tool’s file limits and restrictions are listed above.