Overview
Converts a colour PDF to grayscale so it prints in black and white and does not use colour ink. You choose the resolution and JPEG quality, see a grayscale preview of page 1, and download a rebuilt PDF with every page converted. The conversion runs in your browser with pdf.js and pdf-lib, with progress for each page and a Cancel button.
How It Works
Drop a PDF and a grayscale preview of the first page appears. Choose 96, 150, 200 or 300 DPI and a JPEG quality between 40 and 95 percent, then click Convert to grayscale. Each page is processed in turn and the progress bar shows how far it has got. The downloaded copy ends in -grayscale, and the result shows the file size before and after so you can try a different setting if the file grew.
Step-by-Step Usage Guide
- Drop the colour PDF.
- Check the grayscale preview of page 1.
- Choose a resolution and JPEG quality.
- Click Convert to grayscale and download the result.
Technical Specifications & Standards
Each page is rendered by pdf.js to a canvas at the chosen resolution. Every pixel is then converted to a single gray level with Rec. 709 luminance weights, 0.2126 red, 0.7152 green and 0.0722 blue, which matches how bright colours look to the eye better than a plain average; a pure yellow therefore stays light instead of turning mid gray. Transparent areas are composited over white. The gray page is encoded as a JPEG at your quality setting and placed on a page of the original size with pdf-lib. That is why the warning appears before you convert: the new pages are pictures, so text can no longer be selected, searched or read by a screen reader, links stop working, and vector line art becomes pixels. Higher DPI keeps small text readable when printed but makes a larger file. Keep the original if you might need the colour or the text later.
Targeted Use Cases
- Printing a colour report on a black-and-white office printer with predictable results.
- Saving colour ink when printing slides or worksheets at home.
- Meeting a submission rule that requires grayscale documents.
- Checking how a design reads without colour, for contrast reviews.
Notes & Gotchas
- Use 200 DPI for print and 150 DPI for on-screen reading.
- Keep the original PDF, because the grayscale copy has no selectable text.
- Compare the before and after sizes and lower the quality if the file grew.
Frequently Asked Questions
How do I convert a PDF to black and white?
Drop the PDF, pick a resolution such as 200 DPI for printing, and click Convert to grayscale. The downloaded copy has every page in shades of gray.
Why can I no longer select text after converting?
Each page is rendered to an image so its colours can be converted, which removes the text layer. Keep the original if you need searchable text.
Why did my file get bigger?
Text-heavy PDFs are small because text is stored as characters. As images they take more space. Try 150 DPI or a lower JPEG quality.
Which grayscale formula is used?
Rec. 709 luminance weighting, which gives green the most weight and blue the least, so brightness matches what the eye sees.
Related tools
- Compress PDF - Reduce PDF file size with lossless clean-up or strong image compression at a chosen DPI and quality, with before and after sizes.
- PDF N-up (Pages per Sheet) - Print 2, 4, 6, 8, 9 or 16 PDF pages on each sheet, on A4, Letter, Legal, A3 or A5, with page order, margins, gaps and thin borders. Pages stay vector, so text remains sharp.
- PDF to JPG / PNG - Convert PDF pages to JPG or PNG images at up to 3x resolution, pick a page range and download all pages as a ZIP.
- Watermark PDF - Add a text or image watermark to PDF pages, centred or tiled, with opacity, angle, colour and page range controls.
- Markdown to PDF Converter - Convert Markdown or a GitHub README to PDF with code highlighting, Mermaid diagrams, math, page size, margins and a table of contents.
- Organize PDF Pages - Reorder, delete, rotate, duplicate and extract PDF pages with drag-and-drop thumbnails, then download the new PDF.