# Watermark PDF — Add a watermark to a PDF on Mac

Stamp DRAFT, CONFIDENTIAL or your own text across every page. Part of OneMacTools, 151 private tools in one native Mac app (macOS 26 or later); category: PDF. Runs on your Mac; nothing is uploaded.

Add a large, semi-transparent watermark across every page, diagonally or straight, at the size and opacity you choose.

Page: https://www.onemactools.com/tools/watermark-pdf · Download: https://www.onemactools.com/download · Pricing: https://www.onemactools.com/pricing

## How to use it
1. **Add the PDF.** Drop one or more PDFs onto Watermark PDF.
2. **Type the watermark.** Enter your text, like DRAFT or SAMPLE. If you leave it blank, CONFIDENTIAL is used.
3. **Adjust the look.** Set the opacity and size, and choose whether it runs diagonally across the page.
4. **Click Watermark.** A copy ending in “watermarked” is saved in a dated folder in Downloads › OneMacTools. Check it with the Preview (eye) button.

## Options
- **Text:** The words to stamp across every page. Leave it blank to use CONFIDENTIAL.
- **Opacity:** From 5% to 60% (15% by default). Low values keep the page easy to read; higher values make the mark harder to ignore.
- **Size:** From 24 to 120 pt (64 pt by default). Long text needs a smaller size to fit across the page.
- **Diagonal:** On by default, running the text from corner to corner. Turn it off for a straight, horizontal mark across the centre.

## Tips
- Keep watermark text short. One or two words like DRAFT or DO NOT COPY read better and fit at a larger size.
- Around 10–20% opacity marks the page clearly without getting in the way of reading.
- Put a name or date in the text, like SAMPLE – ACME LTD, to trace where a shared copy came from.
- Filled-in form fields, links, comments and bookmarks are kept. Flatten first with Grayscale & Flatten PDF only if you want the answers locked in place.
- A watermark is visible text, not protection. To stop people opening the file, use Add Password as well.

## Questions
**How do I add a watermark to a PDF on a Mac?**
Drop the PDF onto Watermark PDF, type your text, set the opacity and size, and click Watermark. The text is stamped across the centre of every page.

**How do I mark a PDF as DRAFT?**
Type DRAFT in Text, keep Diagonal on and click Watermark. Every page gets a large, faint DRAFT across it.

**Can I use a logo as the watermark?**
No. Watermark PDF stamps text only. You choose the words, size, opacity and angle.

**Will the watermark hide the content?**
No. It's semi-transparent grey, so the page shows through. Lower the opacity if it's too strong.

**Can people remove the watermark?**
It's drawn into each page of the copy, so it can't simply be switched off. Determined editing could still change a PDF, so don't treat it as security.