Convert a PDF to Grayscale
Turn a colour PDF grey — for cheaper printing, for a consistent look, or to shrink a colour-heavy document. Every page is rendered, converted with the standard luminance formula, and rebuilt into a new PDF. There is also a pure black-and-white mode with an adjustable threshold.
Drop PDF files here or click to select
One or many · a grey copy per file
No PDF handy? Try sample-10-pages.pdf. More free sample files.
The trade-off you are accepting
There is no way to recolour a PDF's text and vector art in the browser without rewriting every content stream — so this rasterises: each page is rendered to an image, converted to grey, and placed on a new page at the original size. The result looks right and prints right, but the text layer is gone. It is no longer selectable or searchable, and screen readers cannot read it.
That is fine for a print-ready file or an archive image, and wrong for a document people will search. If you need to keep the text, do the conversion at print time instead — every print dialog has a grayscale or "black and white" option that leaves the file untouched.
Choosing DPI and quality
- 150 DPI is the sweet spot for office printing and screen reading.
- 300 DPI for anything with small print or fine line art that will be printed properly.
- 96 DPI when the goal is a small file for review.
- Quality 0.85 keeps text edges clean. Below 0.6 you start to see JPEG ringing around letters.
- The output size is reported next to each file, with the change against the original.
Grayscale versus pure black and white
Grayscale keeps 256 levels, so photographs and shading survive and text looks smooth. Pure black and white forces every pixel to one extreme at the threshold you set — which produces a much smaller file and the crisp look of a fax or a photocopy, but destroys photographs and any text rendered in a light colour. Raise the threshold to make more of the page black, lower it to make more of it white.
FAQ
Will the text still be selectable?
No. Pages are rasterised, so the text becomes part of an image. Run OCR on the result to add a searchable text layer back if you need one.
Does grayscale make the file smaller?
Usually yes for colour-heavy documents, and sometimes no for a text-only PDF, where an efficient text page becomes a JPEG image. The size change is reported per file so you can see which happened.
Which formula is used?
The standard luminance weighting — 0.299 red, 0.587 green, 0.114 blue — which matches how the eye perceives brightness and is what image tools use for a "convert to grayscale" command.
What is the threshold in black-and-white mode?
The brightness cut-off: pixels brighter than it become white, darker become black. 170 suits normal text; try 200 for a faint scan and 120 for a dark one.
Is my PDF uploaded?
No. Rendering and rebuilding happen entirely in your browser.
Related tools
- Compress PDF — shrink without changing colour
- PDF to images — export the pages as PNG or JPG
- OCR PDF — add the text layer back
- Auto-crop margins — tidy the page edges
- Flatten PDF — bake in forms and annotations