Guides
How to merge PDF files into one document
Combining PDFs is easy. Getting the page order right is where it goes wrong — here's how to avoid that.
Merging PDFs is one of the simplest document jobs there is, and it still goes wrong constantly — nearly always for the same reason.
The quick version
- Open Merge PDF.
- Drop in two or more PDFs.
- Check the order and fix it with the arrow buttons.
- Merge and download.
Step 3 is the one people skip.
Why the order comes out wrong
When you select several files at once, your operating system hands them over in its own order — usually alphabetical by filename. And alphabetical order isn’t numerical order.
Sorted as text, page10.pdf comes before page2.pdf, because it compares character by character: “1” sorts before “2”. A ten-part document merges with part ten in second place, and you don’t notice until someone else does.
Two fixes:
Pad your numbers. Name files 01, 02, … 10 rather than 1, 2, … 10. With the same number of digits, alphabetical and numerical order finally agree. This is worth doing habitually for anything scanned in batches.
Or just look at the list. The file list in the merge tool is the order you’ll get. Move anything out of place before merging. Thirty seconds of checking beats re-merging.
What merging preserves — and what it doesn’t
Pages are copied exactly, not re-rendered. Text stays selectable, images keep their resolution, and nothing is recompressed. The merged file is roughly the sum of its parts.
Not carried over: bookmarks and the outline tree, form fields, internal links, and document-level metadata. Each source file has its own, and there’s no unambiguous way to combine them. If your source PDFs have interactive forms, fill them before merging.
One thing to watch: pages keep their original dimensions. Mixing A4 and US Letter documents gives you a file with slightly different page sizes — perfectly valid, but visible when printed. If uniformity matters, standardise before merging.
Common situations
Job applications. A CV, cover letter, diploma and references, when the form accepts one attachment. Order matters here more than anywhere — put the CV first.
Expense claims. A month of receipts as one document. Scan or photograph them, convert the images to PDF, then merge.
Signed contracts. The agreement plus a separately signed signature page.
Batch scans. Scanners with a limited feeder produce several files that need reassembling.
Reports written by several people. Chapters combined at the end. Watch for duplicate cover pages and inconsistent page numbering — merging doesn’t renumber anything.
After merging
If the combined file is too large for email, compress it. If you merged the wrong thing, Split PDF takes it apart again — merging is non-destructive, and your originals are untouched.
To reorder pages within a document rather than combining files, split it into individual pages and merge them back in the order you want. Clumsy, but it works without any software installed.
Merging without uploading
The things people merge are precisely the things worth not uploading: signed contracts, ID scans, payslips, medical records. Handing those to an unknown server means creating a copy you no longer control.
The merge tool here runs in your browser. Files are read from your device, combined in memory and written back out as a download. Your documents themselves are not uploaded — once the required converter resources are loaded, the merge takes place locally.