Sumatra PDF dark mode — the honest guide
Sumatra can invert colors, but the feature is hidden and rough around the edges. Here's how to turn it on — and what to do when you need a proper dark file.
How to enable dark mode in SumatraPDF
Quick way: the invert hotkey
- Press
ito toggle inverted colors — white pages become black. - Press
Shift+ito invert everything except images (photos keep their natural colors). - Press the same key again to switch back.
Custom colors: the settings file
For a softer dark theme you have to edit a config file by hand:
- In SumatraPDF, open Settings → Advanced Options… — this opens
SumatraPDF-settings.txtin a text editor. - Find the
FixedPageUIsection and setTextColorandBackgroundColor— for exampleTextColor = #d1d1d6andBackgroundColor = #1e1e20for a comfortable grey-on-dark theme. - Save the file and restart SumatraPDF. The colors apply to PDF pages from then on.
Where Sumatra's dark mode falls short
- It's a display trick, not a file. The PDF on disk stays white — you can't save, print, or send a dark version to your tablet, phone, or e-reader.
- Images go negative. The plain
iinversion turns photos and figures into film negatives. (Shift+iavoids this.) - Rendering bugs. Users report a white line along the page edge in dark mode (open issue in Sumatra's tracker), plus occasional glitches on zoomed or long documents.
- No UI for themes. Custom colors mean hand-editing a settings file and restarting the app — and the inversion is still pure white-on-black, which many people find harsh.
The polished alternative: convert the file
If you read the same PDFs often — textbooks, sheet music, manuals — convert the document once and open the dark version in Sumatra (or any reader) forever:
- Tuned colors: light grey text on near-black, easy on the eyes — not harsh pure-white on pure-black.
- A real file: the converted PDF opens dark everywhere — Sumatra, Acrobat, phones, tablets, Kindle.
- Search keeps working: vector conversion preserves text and OCR layers; nothing is rasterized.
- No edge artifacts: backgrounds are painted slightly past the page box, so no white fringe.
Try it right here — or use the full converter on the home page:
Frequently asked questions
Does Sumatra PDF have a dark mode?
Yes, but it is hidden. Press i in SumatraPDF to invert page colors (Shift+i inverts without images), or set custom TextColor/BackgroundColor values under FixedPageUI in the advanced settings file. There is no checkbox in the normal settings dialog.
What is the Sumatra PDF invert colors shortcut?
Press i to toggle inverted colors, or Shift+i to invert everything except images. Press the same key again to switch back.
Why do my images look like negatives in Sumatra dark mode?
Sumatra's inversion is a straight color negative: photos and illustrations are inverted along with the text. Use Shift+i to keep images normal, or convert the file with a tuned dark theme that keeps images natural-looking.
Can Sumatra export a dark-mode PDF file?
No. Sumatra only changes how pages are displayed; the file on disk stays white. To get a dark PDF you can keep, print, or send to another device, convert the file itself with the tool above.
Why is there a white line at the edge of the page in dark mode?
That is a known Sumatra rendering bug in dark mode (tracked in the project's issue tracker). Converting the file avoids it: the converter paints backgrounds slightly past the page edge so no white fringe remains.