Add a text watermark to a PDF
Mark a document as a draft, a copy or confidential before you circulate it. The text is drawn across every page at the angle, size, colour and opacity you choose — diagonally, straight across the middle, or tiled over the whole sheet so it cannot be cropped out.
How to use the Watermark PDF
- Drop the PDF you want to mark.
- Type the wording — DRAFT, CONFIDENTIAL, a client name, a date.
- Choose diagonal, horizontal or tiled, then set size, colour and opacity.
- Click Add watermark and download the stamped PDF.
Choosing a layout
Diagonal is the classic 45° stamp across the middle of the page: readable, hard to ignore, and it does not sit on any one line of text. Horizontal keeps the mark level, which suits short words on landscape pages and slides. Tiled repeats the text in a grid across the whole sheet; use it when the point is to make the document unusable as a clean copy — a screenshot of any corner still carries the mark.
Opacity is the setting that matters
The default 15% is deliberately faint. A watermark should be unmistakable at a glance yet leave the body text comfortable to read. Between 10% and 25% works for most documents; go to 35–50% only when the file will be photocopied or faxed, because reprographic equipment loses light greys. Above about 60% the mark starts to compete with the content. Note that opacity is applied as a real PDF transparency, not by picking a pale colour, so it behaves correctly over both white paper and dark images.
Size and wording
At 60 pt a word like CONFIDENTIAL is roughly 400 points wide — about two thirds of the width of an A4 page — which is why long phrases need a smaller size. Keep it to one or two words for diagonal and tiled layouts. Everything after the first line break is ignored; if you need two lines, run the tool twice at different sizes.
What a watermark does and does not do
It is a deterrent and a label, not a security control. The text becomes part of the page content and cannot be toggled off in a reader, but anyone determined enough can rebuild the pages as images and paint it out. If the aim is to stop printing or copying, that is a permissions question — and worth reading our honest explanation on the unlock PDF page about how weak those flags are. For genuinely confidential material, control who receives the file.
Character support
The stamp uses Helvetica, one of the 14 fonts built into every PDF reader, so nothing is embedded and the file grows by only a few hundred bytes. Those fonts cover the WinAnsi character set — English, most western European languages, the euro sign and typographic quotes. Characters outside it, including Urdu, Arabic, Hebrew, Greek, Cyrillic and all CJK scripts, are replaced with a question mark and the result box tells you how many were affected.
Frequently asked questions
Can the watermark be removed again?
Not cleanly. It becomes part of the page content, so always keep your unwatermarked original. Equally, treat it as a label rather than protection.
What opacity should I use?
15% for on-screen reading, 35–50% if the document will be photocopied or faxed, where pale greys tend to disappear.
Can I watermark only some pages?
Not in this tool — the stamp goes on every page. Split the file first with Split PDF, watermark the part you want, then merge the pieces back together.
Can I use an image or a logo as the watermark?
Not yet; this tool stamps text only. For a logo, place the image in your source document before exporting it to PDF.
Privacy
This tool runs entirely inside your browser using WebAssembly and the Canvas/File APIs. Your files are never uploaded to ToolFlint or any third party; you can verify this in your browser's network tab or by switching to airplane mode after the page loads. Read how we process files.
Last updated 2026-09-23.