PDF to Grayscale
LocalConvert a colour PDF to grayscale for mono printing
Drag & drop files here or click to browse
PDF • Max 100 MB
Files are processed in your browser and never uploaded
Processing limits
- Rendered PDFs: up to 500 pages, 8,192 px per side, 32 MP per page, 100 MP in total, and 250 MiB of output.
- These are memory budgets, not upload limits — a large file is only ever read by your own browser.
500 pages · 8,192 px/side · 32 MP/page · 100 MP total · 250 MiB output
Privacy First
Your files are processed entirely in your browser. Nothing is uploaded to any server.
How do I convert a colour PDF to grayscale?
Load the PDF and run the tool — there is nothing to configure. Every page is rendered, each pixel is converted to a single brightness value using standard luminance weighting, and a new PDF is built from the greyscale pages. Because the pages are rebuilt as images, the text layer does not survive. Everything happens in your browser.
About the PDF to Grayscale
Convert colour PDF pages to grayscale using the standard luminance weights (0.299 R, 0.587 G, 0.114 B) rather than whatever conversion a printer driver applies. Each page is rebuilt as a flattened lossless PNG at twice its point size, so text, links and form fields are no longer selectable, and a text document usually comes out larger than it went in rather than smaller. The three colour channels are set to the same value rather than rewritten as a single-channel DeviceGray image, so the appearance is gray while the file still carries RGB pixels. Use it when the printed result matters; use Compress PDF when size is the goal.
- Strip colour before printing so a mono laser printer or copy shop is not charged at colour rates for a document with one blue header.
- Neutralise highlighter marks, coloured stamps and branded headers that distract from the text in a review copy.
- Produce a consistent gray rendition using the standard luminance weights rather than whatever conversion each printer driver decides to apply.
- Choose gray over pure black and white when photographs and shading must remain readable rather than collapsing to two tones.
- Keep the colour original: the grayscale copy is a flattened image, so it is a deliverable rather than a working file.
How to use the Grayscale PDF tool
- 1
Upload PDF file
Select PDF file from your device or drag file into the upload area.
- 2
Review files
Review the selected files and continue when they are ready.
- 3
Convert to Grayscale
Run the Grayscale PDF tool to create the PDF output.
- 4
Download the result
Download the finished file. The original file stays on your device and is not uploaded.
Does this keep the text selectable?
No, and it is worth being clear about it. Removing colour from a PDF means touching every mark on the page, so each page is rendered to an image, converted to grey, and written back as a picture. The document looks the same minus the colour, but the text layer, links, and form fields are gone, so the result cannot be searched or copied from. If you need greyscale output that stays searchable, print to PDF with a greyscale setting from an application instead.
How is colour converted to grey?
By weighted luminance rather than a plain average of the three channels. Human vision is far more sensitive to green than to red, and least sensitive to blue, so the green channel contributes most to the resulting brightness and blue contributes least. That is why a saturated red and a saturated green of the same nominal intensity become clearly different greys — and why weighted conversion keeps coloured charts and highlighted text distinguishable where a naive average would flatten them into the same tone.
Is this the same as printing in black and white?
Not quite. Printing greyscale is a decision made at print time and leaves your file untouched, so the next person to print it gets colour again. This produces a genuinely greyscale document — useful when you need to submit a monochrome file, guarantee a print shop cannot bill for colour, or check how a colour-coded design survives without colour. If you need pure two-tone output rather than shades of grey, use the black-and-white tool.
Are my files uploaded when converting a PDF to grayscale?
No. Both the rendering engine and the colour conversion run inside this tab, so a design proof, a marked-up plan, or an internal report is never transmitted in order to have its colour removed. The output PDF is assembled in memory and handed straight to your browser’s downloader.
How to do this offline, on the command line
Ghostscript can convert the colour space rather than rasterizing the page, so text stays text.
Ghostscript
macOS: brew install ghostscript · Debian/Ubuntu: apt install ghostscript
gs -sDEVICE=pdfwrite -sColorConversionStrategy=Gray -dProcessColorModel=/DeviceGray -dNOPAUSE -dBATCH -sOutputFile=gray.pdf colour.pdfUnlike this page, Ghostscript keeps the text layer selectable because it converts colour operators instead of rendering to an image.
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