Threshold a PDF to Pure Black and White
Threshold every page to pure black and white — smallest possible print.
Select a PDF
Click to choose, or drop a file here
You can also paste (Ctrl+V / Cmd+V)
Most tools run entirely on your device
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About converting a PDF to pure black and white
This goes further than greyscale: every pixel on every page is thresholded to pure black or pure white, with nothing in between — the effect you get from an old fax machine or a high-contrast photocopy. It produces the smallest possible file size for print, at the cost of losing any subtle shading, and suits scanned text documents better than anything with photos or gradients.
The tool re-renders every page as an image with pdf.js, applies a brightness threshold to push each pixel fully black or fully white, and rebuilds the PDF from those pages with pdf-lib — entirely in your browser. Because thresholding is aggressive, photos and gradients turn into blotchy black-and-white shapes; this tool is at its best on text-heavy scanned documents, not photographic content.
Supported files
Accepts a PDF. Produces a PDF where every page is pure black-and-white — no greys, no colour.
Is my file uploaded?
No. The conversion runs entirely in your browser with pdf.js and pdf-lib — nothing is uploaded.
How to PDF to Black & White
- 1
Select a PDF
Drop in the document you want converted to black & white.
- 2
Set the threshold
Slide to control how dark a pixel must be to stay black.
- 3
Convert and download
Click Convert to black & white and save it.
PDF to Black & White — frequently asked questions
How is this different from grayscale?+
Grayscale keeps shades of grey; this forces every pixel to pure black or pure white — the smallest possible file and the sharpest fax/print.
Is it reversible?+
No — pages become flat black-and-white images. Keep your original.
Is there a free way to threshold a PDF to pure black and white?+
Yes — this tool thresholds every page entirely in your browser, free and with nothing uploaded.
Can I adjust the threshold?+
Yes — a threshold slider controls how dark a pixel needs to be before it's pushed to black rather than white, so you can compensate for a light or dark original scan.
Do you upload my files to a server?+
No — every tool here processes your files entirely on your device, and nothing is uploaded to a server. The only exception is the AI tools, which send the extracted text (not the file) to Claude to do their work.
Is there a file size limit?+
There's no artificial limit we impose, but since processing happens in your browser, very large files (500+ MB or 1,000+ pages) are limited by your device's memory rather than by us.
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