Use the free Convert PDF to Grayscale below: your PDF never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
Why turn a PDF black and white?
Colour printing is expensive. A colour PDF printed in an office can cost several times more per page than the same document in black and white, and for most text documents colour adds nothing. Reports, contracts, study notes, and forms are just as readable in grayscale. Converting before you print can cut the bill sharply, especially across a long document or a whole class set.
There are other reasons too. Some printers only print in black and white, and their automatic conversion can be ugly — washed out, or oddly dark. Converting yourself gives you a file you can preview, so there are no surprises at the printer. Grayscale files also tend to be smaller and simpler, which helps when emailing or archiving.
How this tool converts
Upload your PDF and choose a quality setting. Each page is drawn to an image, every pixel is converted to its gray value using the standard luminance formula — the one that weights green most, because human eyes are most sensitive to green — and the gray pages are rebuilt into a new PDF. The process runs entirely in your browser: pdf.js renders the pages, and pdf-lib assembles the result. Your file is never uploaded.
The quality setting is a trade-off. Higher quality gives sharper pages but takes longer and makes a bigger file. The middle setting suits most documents. Use the highest only for pages with fine detail, like small diagrams or tiny text.
The one limit you must know
After conversion, the text in your PDF is part of an image. You cannot select it, copy it, or search it. That is the honest price of this method: a true grayscale conversion that works on any PDF, including scanned pages, has to go through images, because a scanned page has no text to convert — it is already a picture.
So keep your original colour PDF. Use the grayscale copy for printing and sharing, and keep the original for editing, copying, and searching. Think of it like a photocopy: perfect for distribution, not a replacement for the master.
When grayscale looks bad — and what to do
Most documents convert beautifully. The cases that suffer are colour-coded ones: charts where red and green lines become similar grays, maps where colour carries meaning, and highlighted text that turns into a gray wash. Before converting a document like that, ask whether colour carries information or decoration. If it carries information, keep the colour version, or check the grayscale preview carefully to confirm the information survives.
Light colours can also disappear. Pale yellow highlighting or light blue text may become nearly white in grayscale. If your document relies on highlighting, darken it before converting, or accept that the emphasis will be lost in print.
Printing tips
Print one page first and look at it under normal light, not just on screen. Screens are backlit and flatter differences; paper shows the truth. Check small text, thin lines, and any diagrams. If a page looks too dark, it may be a page with a coloured background — those backgrounds become gray fills that eat toner. For such pages, the colour original with a “print in grayscale” printer setting may actually use less toner than a converted page with a dark background.
For long documents, consider converting once and reusing the grayscale file for every print run, rather than converting each time. It saves time and keeps every copy identical.
Privacy
Your PDF is processed on your device and never sent to a server. The converted file is built locally and downloaded to you. Close the tab and the tool forgets your document entirely.
Common questions
Will my PDF stay searchable? No. After conversion the text is an image, so search and copy stop working. Keep the original for that.
Does it work on scanned PDFs? Yes. Scanned pages are images already, so they convert cleanly.
Why is the new file bigger sometimes? Image-based pages can be larger than text-based ones, especially at high quality. Use the middle setting for a smaller file.
Can I convert only some pages? Not in this version — the whole document is converted in one run.