How to view a PDF in dark mode

Why a PDF does not simply have a dark mode

A web page can switch to a dark theme because its author wrote two sets of colours. A PDF is a fixed page. The white is white, the black is black, and the viewer app has no instruction for what a dark version should look like. The only way to get one is for the viewer or the operating system to change the colours as the page is drawn.

Two kinds of change are possible. A viewer can replace the page and text colours, which keeps pictures untouched. Or the whole screen can be inverted, which is quicker and more general, and which also flips photographs into negatives unless the smart invert option is used.

Dark mode in a PDF app or browser

1. Open the viewer’s settings or preferences and look for accessibility, display or page colour options. Adobe’s reader, for example, has document colour options in its accessibility preferences, where you can replace the page background and the text colour on screen.
2. Pick a dark background and a light text colour. Choose a soft grey rather than pure white for the text if bright white tires your eyes.
3. Look for an option that only changes black text, or one that leaves images alone, so photographs and diagrams are not distorted.
4. Check how it looks on a page with a table, a chart and an image before you settle on it.
5. Remember that this changes how the page looks on your screen. It does not alter the file, and it does not carry over to a printout.

Dark mode with the system colour filters

• Windows: in Settings, open Accessibility and then Colour filters, and choose the Inverted filter. A keyboard shortcut can switch it on and off once the feature is enabled.
• Mac: in System Settings, open Accessibility and then Display, and use Invert colours. The Smart option leaves images and media as they are.
• iPhone and iPad: in Settings, under Accessibility and Display & Text Size, use Smart Invert so pictures are not flipped.
• Android: in Settings, under Accessibility, look for Colour inversion. A general dark theme only darkens the interface of apps, not the pages inside a PDF.

Why you should not print a dark-mode PDF

A page with a dark background prints as a block of ink or toner. It costs more, takes longer to dry and tends to curl thin paper. Text that is light on dark also becomes harder to read on paper, where the white of the sheet is the brightest thing in the room.

If you want to save ink, print the original light version of the document. If all you have is a dark-background file, change the page colours back in the viewer where possible, or ask whoever made it for the light version. For scans with a grey or cream cast that costs toner, whitening the background is the right tool: it moves the paper towards white and leaves dark ink alone.

If your PDF is faint, dark mode will not fix it

Inverting a washed-out page gives you a washed-out page in negative. Pale grey text on white becomes pale grey text on black. If the text itself is the problem, correct it first with Darken PDF and then read it in whatever colour scheme you like.