How to Merge Multiple PDF Files Into One

Merging PDFs — combining a cover letter, resume, and portfolio into one file, or stitching together scanned pages from separate scans — is one of the most common PDF tasks, and one of the simplest to get right, as long as you know a couple of things going in.

Order matters — and it's easy to get wrong

A merge tool combines files in whatever order you give it. If you're merging more than two or three files, double-check the order before merging rather than after — reordering pages inside an already-merged PDF is more work than just re-arranging the input files first.

Password-protected files

A PDF that requires a password to open generally can't be merged directly — the merge tool can't read its contents any more than you can without the password. If one of your files is protected, unlock it first (you'll need the password), then merge. See Unlock PDF.

Does merging reduce quality?

No — merging just combines pages as they already exist; it doesn't re-encode or compress anything inside them. The merged file's size is roughly the sum of the originals' sizes. If the combined file ends up too large, that's a separate step — compress it after merging, not before (compressing each file separately first can mean compressing twice, with more quality loss than doing it once at the end).

Mixed page sizes or orientations

You can merge files with different page sizes or a mix of portrait and landscape pages — the merged PDF just keeps each page as it was. It's worth checking the result if you're combining very differently-formatted documents, since the visual jump between page sizes can look odd even though nothing is technically wrong.

Try it directly: Merge PDF — runs entirely in your browser, files are never uploaded anywhere.