Convert PDF to Grayscale
Convert color PDFs to clean grayscale to save printer ink and shrink file size. Free, no signup, runs locally.
Key Features
- Perceptual greyscale conversion using ITU-R BT.709 luminance formula (not simple RGB averaging)
- Preserves text sharpness — black text on white background remains crisp after conversion
- File size reduction — greyscale PDFs are typically 40–70% smaller than color originals
- Page range control — convert specific pages to greyscale while keeping others in color
- Adjustable output resolution (72–300 DPI) to balance file size and quality
- Supports color, CMYK, and mixed-mode PDFs
- Batch processing — convert multiple PDFs to greyscale in one session
- 100% browser-side rendering via pdf.js — document never transmitted to servers
About PDF Grayscale
PDF Grayscale converts color PDFs to black-and-white or greyscale — reducing file size, lowering printing costs, and meeting monochrome submission requirements — entirely in your browser. The tool renders each PDF page at high resolution via pdf.js, converts the resulting canvas to greyscale using a luminance-weighted formula (standard ITU-R BT.709), then re-encodes the pages into a new PDF. The greyscale conversion uses the perceptual luminance formula (0.2126R + 0.7152G + 0.0722B) rather than simple averaging, which preserves perceived contrast for text and diagrams. Resulting PDFs are significantly smaller than the originals because greyscale image data is one-third the size of RGB.
Most grayscale converters just average RGB channels, producing washed-out results where colored charts lose contrast. This tool uses the perceptual ITU-R BT.709 luminance formula — the same used by professional printing workflows — so text stays sharp and colored charts remain readable as greyscale. Client-side processing means no upload of sensitive documents.
Who Uses This Tool
- Reducing printing costs by converting color marketing PDFs to greyscale before batch printing
- Meeting monochrome submission requirements for academic journals or government forms
- Archiving PDFs at smaller file sizes for long-term storage systems
- Preparing color reports for printing on black-and-white office printers
- Stripping color from scanned color documents to reduce file size before OCR
- Creating greyscale proof copies of print designs to check ink coverage and contrast
How to Use Convert PDF to Grayscale
- Step 1: Upload your color PDF or drag it into the tool
- Step 2: Choose target resolution (150 DPI for screen, 300 DPI for print)
- Step 3: Select page range if needed (all pages or specific range)
- Step 4: Click "Convert to Greyscale" and download the result
Frequently Asked Questions
Will the greyscale PDF be smaller than the original?
Usually yes — significantly smaller. Greyscale image data is one-third the size of RGB. A 10 MB color PDF often becomes 3–5 MB after conversion.
Will text still be readable?
Yes — the perceptual luminance formula ensures black text on white backgrounds is preserved perfectly. Colored text is converted to its luminance-equivalent grey.
Can I convert only some pages to greyscale?
Yes — use the page range selector to target specific pages. Other pages remain in color.
Why use perceptual conversion vs. simple averaging?
Human eyes are most sensitive to green light. Simple averaging treats all channels equally, making images look too dark. The BT.709 formula weights green higher, producing natural-looking greyscale.