Add a watermark to a PDF

When a watermark helps

A watermark says, on every page, how a document should be treated. The common ones each have a job:

• DRAFT on anything still under review, so an early version is never mistaken for the final one when it gets forwarded.
• CONFIDENTIAL on board papers, HR files, pricing and contracts in negotiation: a visible reminder that the pages aren't for general circulation.
• COPY or DO NOT COPY on duplicates of originals, such as a copy of a certificate sent with an application.
• SAMPLE on templates, proofs and previews you share before a sale.
• PAID on an invoice once it's settled, so it isn't paid twice.

Choosing a layout

Diagonal is the classic: large, faint text across the middle of each page, hard to miss and easy to read around. Straight runs across the middle horizontally, which some people find cleaner on forms and tables. Tiled repeats the text over the whole page, so cropping a page or a picture on it still leaves the mark; it suits image-heavy pages such as photos, floor plans and proofs. Corner puts a small label at the top or bottom of the page, like "DRAFT v3" in the top right, when a full-page stamp would get in the way.

With Fit to the page on, diagonal and straight text is sized for each page to span about 80 percent of it, so a longer word is set smaller. In bold Helvetica that comes to:

For color, gray at 25 to 35 percent opacity is the quiet choice and prints well in black and white. Red is the usual color for DRAFT and CONFIDENTIAL; at low opacity it turns pink, which is still easy to spot. Bold text holds up better at low opacity than regular text.

What a watermark can't do

It's worth being plain about this. A watermark added here is a label, not protection. It is drawn on top of each page as text, so anyone with a PDF editor can delete it, and its words can be selected and copied. It doesn't stop anyone from printing, copying, forwarding or screenshotting the file. PDF permission settings, such as "no printing" or "no copying", don't change that either: they're honored only by software that chooses to respect them. In a PDF you share, there's no setting that reliably prevents copying.

What a watermark does well is make intent obvious and leave a trail: a page printed with CONFIDENTIAL across it is hard to pass off as a public document, and a marked copy is easy to recognize later. If you need to know who leaked a copy, a common approach is to send each recipient their own copy with their name in the watermark text.

What changes in your PDF

Related tools: number the pages with add page numbers, stamp legal productions with Bates numbering, or check what changed between two drafts with compare PDFs. To watermark only part of a long file, split the PDF first or extract the pages you need.