Adding a Watermark to a PDF

What Watermarks Are For

A PDF watermark is text or an image drawn across the pages of a document. It travels with the file and appears on screen and on paper, so the message reaches readers who do not see the email or folder the file came from. Common uses are:

• Status marks such as DRAFT, SAMPLE or NOT FOR DISTRIBUTION, so that an unfinished version is not mistaken for the final one.
• Confidentiality labels such as CONFIDENTIAL or INTERNAL, which remind readers how the document should be handled.
• Ownership: a company name, logo or website on portfolios, proofs and previews.
• Copy identification: a recipient's name or a date on each copy you send out, which makes it easier to see where a forwarded copy came from.

Text or Image Watermark

Text watermarks suit status words, names and dates. They are quick to change and stay sharp at any zoom level. In the LeedyBox tool, text that uses only Western European characters (as in English, French or German) is added as real PDF text with a standard font. Other text, such as Korean, Japanese, Chinese, Thai, Cyrillic or Vietnamese, is drawn with your device's fonts at about 300 dpi and added as an image. It prints clearly but cannot be selected or searched.

Image watermarks suit logos and other graphics. Use a PNG with a transparent background, so that only the logo appears and not a white rectangle around it. A JPG has no transparency, and its background box will show on the page. Choose an image large enough for the printed size: a logo that is 10 cm wide on paper needs roughly 1,200 pixels across for 300 dpi.

Opacity, Size and Placement

A watermark is drawn on top of the page content, so it competes with the text underneath. These starting points keep most documents readable:

Lower opacity lets the page show through. Very light marks may be hard to see on photos or dark backgrounds, so check pages with images as well as pages with text. A diagonal angle crosses lines of text instead of covering one line completely, which helps readability. Avoid placing a solid mark over signatures, figures or small print that readers need.

Tiled Watermarks

A tiled watermark repeats the mark in rows across the whole page. Cropping a single corner or the centre out of a screenshot then still shows part of the mark, which is why tiling is common on preview copies. The price is readability: the page carries much more ink, so use a lower opacity and wider spacing than for a single mark. In the LeedyBox tool the rows follow the watermark's angle and every second row is shifted by half a step, which spreads the copies evenly. Each page reuses the same text or image, so tiling adds little to the file size.

What a Watermark Cannot Do

A watermark is a visible label and a deterrent. It does not protect the content:

• A watermark added as separate content on top of the page, as this tool does, can be selected and deleted with many PDF editors.
• A corner mark can be cropped away, and a light mark can sometimes be reduced with image editing after the pages are converted to images.
• The text underneath can still be copied, unless the page itself is an image.

If the content must stay confidential, decide carefully who receives the file and use access control in the system you share it through, or encryption in a PDF application. Add the watermark before you sign a document: any change to a signed PDF makes its digital signature invalid.

Printing Considerations

Light colours and low opacity look different on paper than on screen. Some printers and toner-saving modes reproduce very pale tints faintly or not at all, and a red mark printed in greyscale becomes a mid grey. Print a test page before you print many copies. Keep corner marks at least about 15 pt (around 5 mm) from the edge, because many printers cannot print right up to it, and remember that "fit to page" printing scales the whole page, watermark included.

To try this, open Add Watermark to PDF, choose your file and adjust the settings while watching the preview. To number the pages as well, use Add Page Numbers; see also Adding Page Numbers to a PDF.

Frequently Asked Questions