How to convert a PDF to black and white or greyscale
1 min read·25 July 2026
Colour printing is more expensive than black and white. Sending a document where colour is irrelevant? With PDFrust's grayscale tool you convert a colourful PDF to greyscale — for printing or as a smaller file format.
When do you choose black and white?
Printing on a black-and-white printer (home or office laser printer) is 5–10 times cheaper per page than colour. Contracts, invoices, and reports where colour adds nothing: send them in black and white. Greyscale PDFs are also slightly smaller than colour PDFs.
Greyscale tool in PDFrust
Open the grayscale tool. Upload your colour PDF. Click Convert. PDFrust converts all pixels to greyscale — the text layer and vector content remain black. Download the greyscale PDF. File size typically drops 10–30%.
PDF grayscale
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Greyscale vs. black and white (1-bit)
Greyscale has 256 shades of grey (8-bit). "Black and white" in the strict sense is 1-bit: only pure black or pure white, no shades. For text documents 1-bit is ideal (smallest files). For photos choose greyscale to preserve detail. The grayscale tool delivers greyscale.
Selective colour conversion
Want to convert only certain pages to greyscale and leave others in colour? Use the organize tool to split the PDF by page, convert the desired pages with grayscale, and merge everything afterwards with merge.
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