Watermark PDF

What a watermark is for

A watermark labels a document's status or ownership in a way that travels with every copy. DRAFT on a contract stops a working version being mistaken for the signed one. CONFIDENTIAL or INTERNAL reminds every reader of the document's handling rules. SAMPLE or SPECIMEN on a certificate or a design proof makes it useless as the real thing. A logo marks a brochure or a report as yours.

A personalised watermark — “Prepared for A. Sharma, 3 March” — is the strongest deterrent of all for documents shared with a few people, because a leaked copy identifies who it came from. It is a one-minute job per recipient here, with nothing uploaded.

Getting it to look right

Opacity does most of the work. Between 15% and 30% a diagonal watermark is unmistakable but leaves the text beneath readable; above 50% it starts to compete with the content. A 45° diagonal across the centre is the classic DRAFT layout, and at around 60 to 90 points it spans an A4 or Letter page without touching the edges.

Tiling repeats the mark in a brick pattern across the whole page. It is the hardest to crop out or cover, which is why stock-photo proofs use it, and it suits short words or a small logo at low opacity. The nine positions put a single mark in a corner or along an edge — a discreet logo bottom right, a status label top centre — measured from the edge by the distance you set.

Positions are measured on the page as it is displayed. A scanned page stored sideways and rotated for viewing gets its watermark in the corner you chose and reading the right way up, rather than running down the side.

For an image watermark, a PNG with a transparent background works best, because the transparent areas stay transparent on the page. A JPEG logo will bring its white rectangle with it; lower the opacity or use the logo as a tiled pattern if that is all you have.

Over the content, or behind it

Over the content is the default and always visible: the watermark is drawn after everything else, on top. It is the only choice that works on scanned documents.

Behind the content draws the watermark first, so the page's own text and images are painted over it — the effect of printing on watermarked paper, with text staying perfectly crisp. The catch is that anything on the page with an opaque background covers it. On a scan the whole page is one opaque photograph, so a watermark behind it is completely hidden. Use the preview: it shows the real output, so if the mark disappears there, it will disappear in the file too.

What a watermark does not do

It does not lock the document. A watermark is page content, and anyone with a PDF editor can delete an overlay or paint over a corner mark; a tiled pattern only makes that tedious. If the goal is to stop copying, printing or editing, add a password with Protect PDF as well.

The text is drawn with the standard PDF fonts — Helvetica, Times or Courier — so nothing needs embedding and the file barely grows. Those fonts cover Western European Latin letters; characters they cannot draw, such as Devanagari or Cyrillic, are reported and left out. For a watermark in another script, make an image of the text and use the image option.

Nothing is re-rendered: the original pages keep their text, fonts and images exactly as they were, and stay searchable. The watermark itself is real text, so it is searchable too — a reader can find the word DRAFT in the document.