How to read a PDF in dark mode

Your phone, browser and operating system can all be set to dark mode, and then you open a PDF and get a bright white page. That is because a PDF describes exactly what each page looks like, including its white background, and most viewers draw it faithfully. To read it with light text on a dark page, either the viewer has to repaint it or the file has to change.

Option 1: a viewer setting

Some readers can repaint pages for you. Adobe Acrobat Reader has an accessibility preference to replace document colours, and many e-reader and tablet apps offer a night or inverted mode. This is the best option if your app has it, because the file stays untouched. The catch is that it only works in that app, and the setting often resets.

Option 2: make a dark copy of the file

1. Open Invert PDF Colours and add the PDF.
2. Download the inverted copy: white pages become black and black text becomes white.
3. Open that copy in any viewer, on any device, for night reading.

Because the change is in the file, it works everywhere: in a browser, on a phone, on an e-reader that ignores themes. The conversion runs in your browser, so the document is not uploaded.

What happens to images and colours

• Photographs become negatives. Faces look strange. For a text-heavy book that hardly matters; for a photo-heavy brochure, a viewer setting is better.
• Colours flip to their opposites. Blue links turn orange and red warnings turn cyan. Charts remain readable but the colour key changes meaning.
• Scanned pages invert well, but the grey paper of a scan becomes dark grey rather than black. Converting to grayscale first can give cleaner contrast.

Make it easier to read on a small screen

Dark mode helps at night, but on a phone the bigger problem is often wide white margins that shrink the text. Trim them first with Crop PDF Margins, then invert. The text fills more of the screen, so you zoom less. The guide to reading PDFs comfortably on a tablet covers the rest of the set-up.

Which documents invert well

• Novels, reports, contracts and course notes: almost entirely text, so they invert cleanly.
• Code listings and technical manuals: fine, though syntax colours change.
• Maps, colour-coded charts and photo books: better left as they are, or read with a viewer setting that only repaints the background.

Comfort tips

• Pure white text on pure black can look harsh. Turn screen brightness down rather than reading at full brightness in a dark room.
• If your phone has a warm-colour night setting, use it as well; it changes the screen, not the file.
• Keep the original for printing. An inverted PDF prints mostly black and drains toner.