How to convert a PDF to black and white
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Contents
To make a PDF black and white, open Grayscale PDF, add your PDF, choose an output quality, press Convert to grayscale, and download the copy. Every page comes back in shades of gray, ready for a monochrome printer or a portal that asks for grayscale files.
Shades of gray, not pure black and white: each pixel becomes a brightness value that counts green most and blue least, so pure red and pure green end up as two different grays. Nothing is pushed to solid black or white, so photos and shaded charts keep their tones.
The conversion runs in your browser with pdf.js, so your PDF stays on your device and there is no account to create. It takes one PDF of up to 100 MB.
Step by step
- 1Open the Grayscale PDF tool.
- 2Drop your PDF on the panel that says “Drop your PDF here, or browse”, or click it to choose the file.
- 3Under Output quality, choose Screen (96 DPI) or Print (150 DPI). Print is selected to start; Screen draws fewer pixels per page and usually makes a smaller file.
- 4Press Convert to grayscale. A progress count follows each page, and the new PDF is put together after the last one.
- 5Press Download grayscale PDF. The copy is named after your file, so report.pdf becomes report-grayscale.pdf.
Every page becomes an image
The tool draws each page to an image, turns it gray, and builds a new PDF from those images alone, each page at the size the original shows it. Each page image is stored as a single-channel gray image, either losslessly compressed or as a JPEG, whichever is smaller for that page.
So the copy is for printing or submitting, not for editing. Text can no longer be selected or searched, sharp vector lines become pixels, and links and bookmarks do not carry over. Form fields and comments are painted in from their saved appearance, so they can no longer be filled in or clicked. The new file's title is the original's with the word grayscale added in brackets, as in Annual report (grayscale), or is made from the file name when the original has no title. Keep the original alongside it.
Why the file can get bigger
A page of text is a few drawing instructions in the original and a full picture in the copy, so a text-only PDF usually grows, often by a lot. A scanned or photo-heavy PDF can shrink instead. The result shows both sizes, and when the copy is larger it says so: “Pages are now images, so text-based PDFs usually get larger.”
Screen (96 DPI) draws fewer pixels per page than Print (150 DPI), so it gives a lighter file that reads well on a monitor. Print keeps small type and fine lines crisper on paper.
Printers, portals and charts
Converting before you print sends the printer gray pixels instead of leaving the color-to-gray mapping to its driver, and you can check the result on screen first. A print shop's or a portal's check that reads the declared color space reports grayscale, because no page image is stored in color. A check that also expects live text or vector artwork will not find any.
Two chart series told apart only by hue, with similar brightness, come out as nearly the same gray. A quick conversion flags a chart that needs patterns or labels before it goes on black-and-white handouts.
Common questions
Will the pages be pure black and white, with no gray?
No. The tool converts to grayscale: every color becomes a shade of gray, and nothing is forced to solid black or white. Black text on a white page stays black on white; photos, colored areas and shading become gray tones.
Is my PDF sent anywhere when I convert it?
No. Drawing the pages, turning them gray and building the new PDF all happen in your browser tab, so the PDF stays on your device. The page and its processing engine load over the network, and parts of the engine are fetched the first time a step needs them. The processing itself runs on your device. Rendering a page that holds a JPEG 2000 or JBIG2 image, as scanned documents often do, downloads an image decoder from our site the first time it is needed, and that step needs a connection. Chinese, Japanese or Korean text whose font is not embedded in the PDF needs a character map, downloaded from our site the first time it is needed, and that step needs a connection.
Can I still select or search the text afterwards?
No. Each page is stored as one image, so the text is part of the picture. OCR PDF can add a recognised text layer to the gray copy, but it runs on our secure server rather than in your browser.
Why is the gray PDF bigger than the original?
Because every page is now a picture. A text-only PDF usually grows, while a scanned one can shrink. Screen draws fewer pixels than Print and usually makes a smaller file.
Does it work on password-protected PDFs?
No. Any encrypted PDF is turned away when you choose it, including one that opens without a password but restricts printing or copying, and the message says which lock it has. Unlock PDF removes the encryption if you give it the password, but it runs on our secure server; bring the unlocked copy back here.