PDF merging guide: order, quality and limits

What does merging PDF files do?

Merging means taking two or more separate PDF documents and turning them into a single file whose pages follow one another. The pages of the first file come first, then the second file's pages, and so on. The result opens like any other PDF and is not tied to the source files.

PdfMerge does this in a single step: you upload the files, set their order and download one combined document. There are no modes to learn, because the tool does exactly one job.

How to merge PDFs step by step

The whole job takes four steps on one screen:

• Upload: select two or more PDFs, or drag and drop them onto the window. Files may be 100 MB each at most.
• Order: the file list shows your picks; use the arrow buttons on a file to move it earlier or later.
• Run: press the run button. The pages are copied into one document in the list order.
• Download: the merged PDF downloads as a single file, named after the first file in your list.

Getting the order right

The only decision merging asks of you is the sequence. The file that sits first in the list contributes the first pages of the merged document; the second file's pages follow it, and so on. Pages inside each file always keep their own internal order — a file is never shuffled.

If the order is wrong, you do not need to start over: move a file with the arrow buttons and run again. Naming helps here too — because the merged file takes its name from the first file in the list, putting the 'main' document first gives you a tidy file name.

What is preserved, and what is not

Pages are embedded into the new document as they are: the tool does not redraw them, turn them into images or compress them again. Text stays selectable, vector graphics stay sharp and embedded images keep their original quality — the merge is lossless.

What does not carry over are interactive extras: clickable links, bookmarks and form fields live outside the page content and are not copied. The merged document keeps the exact look of every page, but it is a flat document.

Mixed page sizes are fine: if one file is A4 portrait and another is letter landscape, each page keeps its own size and orientation in the merged document.

Limits and large jobs

A single run takes up to 20 files and 1,000 pages in total, and no file may be larger than 100 MB. These bounds keep merging fast and reliable in the browser.

If your job is bigger, split it into groups: merge the first group into one PDF, then the next, and finally merge those results together. Two short runs get you the same document without hitting the limits.

Encrypted or damaged files

A PDF that is encrypted with a password or damaged cannot be read, so it cannot be merged. When this happens the tool stops and names the file that caused the problem, so you can remove just that file instead of guessing. Save an unlocked copy of the document — most PDF viewers offer this — and run the merge again.

Example: the month-end accounting bundle

Say you have twelve invoices and one summary sheet as separate PDFs. Drop them all onto the window, move the summary to the top with the arrow button and run. You get a single document that opens on the summary and walks through the invoices in order — one file to send, named after the summary with a -merged suffix.

The same pattern works for job applications (CV first, then cover letter, then certificates) and for scanned chapters that belong back in one book.

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