How to add a watermark to a PDF
- Write a short label
One or two words. 'DRAFT', 'REVISION COPY', 'NOT FOR CIRCULATION'.
- Set the opacity low
0.12 to 0.18 is visible on every page and still lets you read the text underneath.
- Decide whether to tile
Tile if the label needs to be hard to remove; a single diagonal is cleaner to read around.
- Stamp and read a dense page
The busiest page is where a watermark becomes a problem, so check that one.
Why this matters for exam and study documents
If you write your own practice paper and hand copies to a study group, stamping 'PRACTICE - NOT AN OFFICIAL PAPER' across it prevents a genuinely awkward misunderstanding later.
What is kept, what changes, and what this will not do
These change how a document presents itself rather than what it contains - with one important exception, which is that cropping hides content without removing it.
Kept
- All existing page content
- The searchable text layer of the original
Changed
- A text object is drawn over each selected page
- Printing uses more toner, particularly when tiled
- Dense pages become harder to read at high opacity
Limits
- A watermark offers no security. It can be removed by anyone with a PDF editor.
- Image watermarks and logos are not supported here - text only.
Questions and answers
Can a watermark stop someone copying my document?
No. It is a visible label, not a lock. If you need to restrict what people can do with a file, use Protect PDF, and understand that even that relies on the reader honouring the restriction.
Can I remove a watermark from someone else's PDF?
Not here. A watermark is merged into the page content and removing it means editing the page. More to the point, a watermark usually states the document's licence or ownership, and removing it to pass the document on is not something this site is going to help with.
What opacity should I use?
0.16 by default. If the document will be photocopied, go up to 0.25 - copiers lose faint tones.