Remove colour from PDF: grayscale conversion online

1 min read·25 July 2026

Need to print on a black-and-white printer, or reduce file size by stripping colour? PDFrust converts any colour PDF to greyscale in one click — no quality loss on text and line art.

When to convert to grayscale

Printing on a black-and-white printer where colour won't reproduce. Documents with black-and-white requirements (e.g., certain official or notarial forms). Reducing file size — colour images are significantly larger than greyscale equivalents.

How the grayscale tool works

Upload your PDF to the grayscale tool. It processes every page and converts all colour information to grey values. Text remains sharp black, images convert to greyscale tones. The result downloads as a new PDF.

PDF grayscale

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Greyscale vs. pure black and white

Greyscale preserves tonal gradations (photos still look realistic). Pure bitmap black and white converts every pixel to either fully black or fully white — sharp for line art, but photos look gritty. The grayscale tool uses greyscale for best visual quality.

Combine with compression

After converting to greyscale, compress the PDF further. Greyscale images are smaller than colour equivalents, so the combination yields a significantly smaller file.