How to Merge Multiple PDFs Into One Document

Get the files ready first

One file is easier to send, approve and archive than seven. Merging is simple when the pieces are ready, and the usual problems, such as pages in the wrong order or a file that will not load, are easy to avoid with a minute of preparation before you open Merge PDF.

• Turn everything into a PDF. Merge PDF accepts PDFs only. Convert documents with Word to PDF and photos or scans with JPG to PDF first.
• Number the filenames in reading order. Names such as 01-cover-letter.pdf, 02-resume.pdf and 03-certificates.pdf let you sort the whole batch with one click. The sort understands numbers, so 2 comes before 10.
• Unlock protected files. A PDF that asks for a password cannot be merged until you remove it with Unlock PDF, which needs the current password.
• Note each file’s page count. Add them up. That total is what the merged file should have, unless you leave pages out on purpose.

Merge PDFs step by step

1. Add the files. Open Merge PDF and select Choose PDF files, or drag the files onto the page. You can add up to 100 PDFs of up to 50 MB each, 100 MB in total. Each file is checked in your browser and appears as a card with its page count.
2. Put them in order. Drag a card to a new position, open its Move menu to send it up, down or to a numbered position, or select Sort A–Z. Each card shows which pages of the final document it will fill.
3. Leave out pages you do not need. Select Choose pages on a card. Untick pages, or type a range such as 4, 1–2 to pick and reorder them in one go. You can rotate sideways pages here too.
4. Preview the sequence. Select Preview page order to page through the final document before you merge.
5. Name the result. Type a name under Output file name.
6. Merge. Select the Merge button, which shows the number of files, such as Merge 3 PDFs.
7. Check and download. Select Preview merged PDF, then Download PDF. If something is out of place, Edit merge takes you back with every file still loaded.

Undo and Redo work throughout, including with Ctrl+Z, so you can rearrange freely.

What merging keeps and what it changes

Merging copies pages from each source into a new file. The pages arrive intact, but a few features that belong to a whole document, not to a single page, do not come along.

Swipe the table sideways to see every column.

Merge PDF tells you about these before you start. A card whose file contains form fields, bookmarks or a signature carries a short note saying what will happen to them. Keep the original files if you will need those features again.

Check the merged file

1. Count the pages. The result screen shows the total. It should equal the sum you worked out earlier.
2. Look at every seam. For each source, find its last page and the first page of the next one. A file added twice or left out shows up here.
3. Search for a phrase from each source. If Ctrl+F finds it, the text came through as text.
4. Check the size. Merging does not compress anything, so expect the result to be close to the combined size of the sources.

In our sample, a three-page file followed by a one-page file produced a four-page result. Page 3 is the last page of the first file, and page 4 is the first page of the second.

To try it with the same files, download sample A, sample B and the merged result.

Fix common merge problems

Pages are in the wrong order

Select Edit merge, drag the cards into place and merge again. If only a few pages inside one file are out of order, reorder them in Choose pages by typing the sequence you want.

Some pages are sideways or a different size

Merging keeps each page as it was, so a landscape page stays landscape and an A4 page stays A4. Rotate pages in Choose pages before you merge, or with Rotate PDF afterwards. Mixed paper sizes are harmless on screen but can print with uneven margins. To make them match, export the source documents again at one paper size; A4 versus US Letter explains the difference.

A file is rejected

The card shows the reason. A password-protected PDF needs unlocking first. A damaged file may open after Repair PDF, or after you export it again from its source. A dynamic XFA form, a kind made with Adobe’s form designer, cannot be merged safely; save a flat copy from the application that created it and add that instead.

The batch is too large

The limits are 100 files, 50 MB per file, 100 MB combined and 10,000 pages in the result. If you are over, shrink the heaviest files with Compress PDF before you add them.

A card says “Possible duplicate”

You have added two files with the same name, size and date. Remove one, unless you really do want the same pages twice.

Finish the document

Each source keeps the page numbers that were printed on it, so a merged file can run 1, 2, 3, 1, 2. To add one continuous sequence, send the result to Page Numbers. If the combined file is too heavy to email, run it through Compress PDF. To remove or move individual pages later, use Organize PDF. The result screen offers all three as next steps, so you do not have to select the file again.

For a long packet with sections and appendices, organizing large PDF documents covers ordering, numbering and extraction in more detail.

When another tool is the better choice

• You want to slot pages into the middle of a document. Organize PDF also works in your browser. Open the main PDF, then use Add another PDF to place pages before or after any page, from up to 10 PDFs and 100 MB in total.
• You need bookmarks or working form fields in the result. Use a desktop editor. Adobe Acrobat can keep both when it combines files, and the free PDFsam Basic lets you choose how bookmarks and forms are handled.
• You only need a few pages from a long file. Extract them first; see how to extract pages from a PDF.
• You are on a Mac and offline. Preview can combine PDFs when you drag page thumbnails from one document’s sidebar into another.

Frequently asked questions

Does merging PDFs reduce quality?

No. Pages are copied as they are. Text stays text, and images keep their original resolution.

How many PDFs can I merge at once?

Up to 100 files in one merge, with 50 MB per file, 100 MB combined and 10,000 pages in the result.

Can I merge only certain pages from each file?

Yes. Select Choose pages on a file’s card and untick the pages you do not want, or type a range. The card then shows how many of its pages are included.

Will the merged PDF keep my bookmarks and form fields?

Bookmarks, yes: each file’s bookmarks are kept in merge order, and links between its pages still work. Form fields, no: filled-in values become fixed text on the page. If the form has to stay fillable, combine the files in a desktop editor instead.