Skip to main content
VellumPDF

Convert a PDF to grayscale

Less ink, lighter files, a crisp printed result.

Your files never leave your device

Drop your PDF here

or click to browse your files

How to convert a PDF to grayscale, step by step

This tool redraws every page in grayscale using perceived luminance, a method that preserves contrast rather than averaging colors.

  1. Drop your PDF

    Drag the file in, or click to browse for it. A before/after preview of the first page appears right away.

  2. Choose the resolution

    150 dpi for screen reading or a draft, 220 dpi as the recommended balance, 300 dpi for professional printing — the higher the resolution, the heavier the file.

  3. Click “Convert to grayscale”

    VellumPDF redraws every page as a gray image at the chosen resolution; progress is shown page by page on a long document.

  4. Download the result

    The weight before and after conversion is shown next to the download button, for an at-a-glance comparison.

The document produced is an image: its text is no longer selectable or searchable, and forms, links and bookmarks aren’t preserved. To get searchable text back, run the result through text recognition.

Frequently asked questions

How does VellumPDF convert a colour PDF to grayscale?

It computes the perceived luminance of every pixel, a method that preserves the original contrasts — a green logo and a blue background do not end up as the same shade of grey. Three resolutions are offered, from 150 dpi for on-screen reading to 300 dpi for professional printing.

Does the grayscale PDF keep its text selectable?

No, the conversion produces a document made of images: the text is no longer selectable, and optical character recognition (OCR) is needed to make it searchable again. That is the trade-off of this method, which faithfully preserves the contrasts.

Which resolution should I choose, and is the processing free?

150 dpi suits on-screen reading, 300 dpi suits professional printing at the cost of a larger file. The tool is free, and the calculation happens in your browser, without the document being sent to a server.

Which conversion formula is used?

Perceived luminance (Rec. 601), which weights red, green and blue according to the eye’s sensitivity rather than taking an average. A red block and a blue block with the same “average” do not look equally light; this weighting stops them coming out identical and unreadable once in grey.

Which resolution should I choose?

220 dpi is the recommended balance: crisp text in print, reasonable file size. 150 dpi is enough for on-screen reading or a draft print. 300 dpi targets professional quality, with a file about twice as heavy as at 220.

Why convert a document to greyscale?

For printing, first of all: a black-and-white printer renders some colours badly, and a light yellow can vanish altogether. Checking the grey rendering before printing saves you discovering the problem across three hundred pages. It also makes a document full of colour screenshots noticeably lighter.