PDFMerge

Merge PDF Files Online – Combine PDFs Into One Free

To merge PDF files, add them to the tool above in the order you want, click Merge, and download the single combined PDF. The result has every page from every file, one after another, so a 10-page file and a 6-page file become one 16-page document.

Merging sounds like a ten-second job, and it usually is. The mistakes come from what happens before and after: files in the wrong order, a merged document too heavy to email, page numbers that no longer match the table of contents. This page covers how to merge PDF files and the small decisions around it, so the combined file comes out right the first time.

How to merge PDF files online

1. Put your files in order. Decide which PDF comes first, second and third before you upload anything.
2. Check the filenames. If the order matters, rename the files with a number at the start (the next section explains why).
3. Add your PDFs. Click the upload area or drag the files onto it.
4. Check the order on screen. The first file becomes the first pages of the merged PDF.
5. Click Merge and download. Scroll through the result and confirm the page count equals the total of your files.

What usually goes wrong

• The files merge in the wrong order. Fixing it afterwards means starting over, so look at the order before you click Merge.
• The merged file is too big to send. The result is roughly the combined size of your files, and scanned pages add up fast.
• Pages come out in different sizes. If one file is A4 and another is Letter, each page usually keeps its own size. Check before you print.
• A locked file doesn’t load. Many merge tools can’t read a password-protected PDF. Remove the password in the program that created it, then try again.

Prepare your files before you merge PDF documents

Five minutes of preparation saves a redo. Go through the files you plan to merge and check these points.

Decide the order, then lock it in with filenames

Rename your files with a number at the start: 01-cover.pdf, 02-report.pdf, 03-appendix.pdf. Files that sort alphabetically then line up in the order you intended, and you won’t have to drag them around.

Use two digits, not one. Computers sort names letter by letter, so a file called 10-appendix.pdf lands before 2-report.pdf. Writing 01, 02 and 10 avoids that. For dated documents such as invoices, put the date first in year-month-day form (2026-03-15-invoice.pdf), which sorts chronologically on its own.

Remove what you don’t need

Double-sided scanners often produce a blank page for every single-sided sheet. Cover pages get duplicated, and old drafts hide inside folders. Delete or leave out anything that shouldn’t be in the final document. If only part of a file belongs in the merge, pull out only the pages you need first and merge the extract.

Check page size and orientation

A landscape spreadsheet printout next to portrait text pages is fine on screen but awkward on paper. If the document is going to be printed, find out now whether mixed orientations or sizes will cause trouble, since fixing it later is harder than fixing it in the source.

Keep the originals

Merging creates a new file and leaves your source files alone. Don’t delete the sources after merging. If a reader asks for a corrected appendix, you can replace one file and merge again in a minute.

Where your pages land when you merge PDF files

It helps to know where each file ends up, especially if the document has a table of contents or other people refer to page numbers. Here is an example with three files:

The report that started on its own page 1 now starts on page 3. A sentence in that report saying “see page 5” now points at page 7 of the merged file. If the report has printed page numbers, they still say 1 to 24 while the PDF viewer says 3 to 26. That mismatch is the most common source of “I can’t find the page you mean” emails, so mention it in your message or renumber the whole document after merging.

How big will the merged PDF be?

Merging stacks pages together without throwing anything away, so the result is roughly the sum of the originals. Three files of 8 MB, 12 MB and 15 MB give you a PDF of around 35 MB. Gmail, for example, caps sent attachments at 25 MB per email on most accounts, and other providers set their own limits. Here is how it plays out with typical content:

These sizes are illustrations, not measurements, and your files will differ. The pattern holds, though: text pages are small, and scanned pages are heavy. Forty pages of the same document can be 4 MB or 60 MB depending on how they were scanned.

If the merged file is over the limit, you have three choices. Merge fewer files and send the rest in a second email. Share a download link from a cloud drive instead of attaching the file. Or merge everything and then split the PDF into smaller parts that each fit, with the break points where you choose.

Merge first, then number the pages

Once your files are joined into one document, you can add page numbers to the PDF so a long file stays easy to navigate. Do it in that order. If you number each file separately and merge afterwards, the numbering restarts at 1 at the start of every file, and you get 1 to 24, then 1 to 9, then 1 to 2 inside one document.

The same logic applies to anything stamped on the pages: headers, footers, watermarks, Bates-style reference numbers. Finish the merge, then add them once.

Merging scans, photos and TIFF files

This tool lets you merge PDF files. If your pages are JPG or PNG images, convert the photos to PDF first, then merge the results with your other documents. Doing the conversion first also lets you control the order of the images before they become pages.

Scanners that save multi-page TIFF files need the same step. Convert the TIFF scans to PDF, and each TIFF page becomes a PDF page in its original order, ready to merge.

One limit to keep in mind: merging does not make scanned pages searchable. A scan is a picture of text, and joining pictures together still leaves you with pictures. Searching inside the merged file only works if the pages went through optical character recognition first. If people will need to search the combined document, run that step on the scans before you merge.

What merging can do to links, bookmarks and forms

Depending on how the files were created, a PDF can carry clickable links, a bookmark panel, or fillable form fields. When you merge, a tool may keep some of these and drop others. Test the result before you rely on it:

• Click a few links in the merged file, especially any clickable table of contents. Links that jump to a page inside the original file can end up pointing at the wrong place once the page numbers shift.
• Open the bookmark panel in your PDF viewer and see whether the outline survived.
• If a file contains a form people must fill in, check that the fields still work, or fill the form first and merge the completed copy.

Situations where you should merge PDF files

Job applications. Many portals want one file: cover letter, CV and certificates. Sending four attachments invites a missing one. One merged PDF in the right order removes the problem, and the recruiter opens a single document.

Month-end invoices. Twelve invoices arrive as twelve files. Merge them into one yearly PDF for your accountant, named with the year first, and one file replaces a folder.

Signed contracts. The body of the agreement often comes in one file and the signature page in another. Join them so the signed copy is one complete PDF that you can file and forward without anything going missing.

Study notes. Lecture slides, your own notes and past papers for one course can become a single revision file. Number the files so the order follows the syllabus.

Insurance or expense claims. A claim form, receipts and photos of the damage belong together. Convert the photos first, merge everything in the order the form lists its attachments, and submit one file.

When you should not merge

You won’t always want to merge PDF files. Keep them separate in these cases:

• The files go to different people. If a client should see their invoice but not another client’s, a merged file shares everything with everyone. Don’t combine documents with different audiences.
• Parts will change at different times. If the appendix is updated weekly and the report is final, keep them separate so you can replace one without redoing the other.
• Each file needs its own signature or approval. Signing tools work on one document at a time, and a merged file mixes up the audit trail.
• The result would be huge. A 200 MB file is hard to open on a phone, whatever the tool.

Name and save the merged file

A file called merged.pdf or combined-final-v2.pdf helps nobody six months later. Name the output for what it contains and when: 2026-annual-invoices.pdf, or application-jane-doe-2026-10.pdf. Put the date in year-month-day form so files sort in order, and use hyphens instead of spaces, which survive email and web uploads more reliably.

Once you merge PDF files, store the result next to the folder of source files, so you can find the originals if you need to rebuild it.

Checklist before you send the merged PDF

1. The page count equals the sum of your files.
2. The first and last page of every original appear in the right place.
3. No blank or duplicate pages slipped in.
4. Text is sharp on a couple of pages that came from scans.
5. Clickable links, bookmarks and form fields still work, if you used them.
6. The file size is under the limit of the system you are sending it through.
7. The filename describes the content and the date.

Merge PDF: common questions

How do I merge PDF files into one?

Add your PDFs to the tool, check that they are in the order you want, click Merge, and download the combined file. Every page from every file appears in the result, one file after another.

How do I put the files in the right order?

Rename the files with a two-digit number at the start, such as 01, 02 and 03, before you upload them. Then check the order shown on screen before you click Merge.

Does merging PDFs reduce quality?

Merging joins pages that already exist, so text and images should look the same as in the originals. Still, scroll through the result and compare a couple of pages with the source files before you send it.

How big will the merged PDF be?

Roughly the combined size of your files. Three files of 8 MB, 12 MB and 15 MB produce a PDF of around 35 MB. Text pages are small, and scanned pages make the file much larger.

Why are my page numbers wrong after merging?

Numbers printed on the original pages stay as they were, so each file keeps its own numbering. Merge first, then add one set of page numbers to the whole document so they run in a single sequence.

Can I merge PDFs and images together?

Convert the images to PDF first, then merge them with your other files. That keeps every page in the same format and the same order.

Can I merge a password-protected PDF?

Many merge tools can’t read a locked file. Remove the password in the program that created the PDF, merge the unlocked copy, and add protection to the combined file afterwards if you need it.

Can I undo a merge?

You can separate the combined file again by page range. Splitting at the original page boundaries gives you files that match your sources, as long as you remember where each one started.

Ready to merge PDF files? Scroll back to the tool at the top, or browse the rest of our free PDF and image tools.