How to Convert a PDF to Black and White
Mac Preview (free)
- Open the PDF and choose File → Export.
- In Quartz Filter, pick Black & White or Gray Tone.
- Save under a new name and check the result.
Adobe Acrobat
To print, tick Print in grayscale (black and white) in the Print dialog; choose the Adobe PDF printer to save a grayscale copy. Acrobat Pro can also convert the file itself with Print Production → Convert Colors and a grayscale profile.
Ghostscript (free, command line)
Grayscale PDF: gs -sDEVICE=pdfwrite -sColorConversionStrategy=Gray -dProcessColorModel=/DeviceGray -o gray.pdf input.pdf. For pure 1-bit pages, render to fax-style TIFF: gs -sDEVICE=tiffg4 -r300 -o bw.tif input.pdf. The -r300 flag sets the resolution; read what 300 vs 600 DPI means before choosing a higher value.
Printer settings
If you only need paper copies, choose Grayscale or Black and white in your printer’s print dialog. The PDF itself stays in color.
The PDF to JPG converter on this page renders the first page as a color JPG and has no grayscale option. If you need sharper page images for print, see our guide to DPI settings for PDF to JPG.
Why Convert to Grayscale?
There are several practical reasons to convert color PDFs to grayscale:
- Save printer ink: Color ink cartridges are expensive. Grayscale printing uses only the black cartridge, saving all color ink entirely. For offices that print hundreds of pages daily, the savings are significant.
- Reduce file size: Grayscale images have one color channel instead of three (RGB) or four (CMYK), so the raw image data is a third or a quarter of the size. Compressed files shrink less predictably.
- Meet submission requirements: Some courts, government agencies, and academic institutions require grayscale or black-and-white document submissions.
- Improve text readability: Removing color distractions can make text-heavy documents easier to read, especially for dense reports and legal documents.
Grayscale vs Black & White vs Monochrome
These terms are often confused but describe different conversion modes:
| Mode | Colors | Best For | File Size |
|---|---|---|---|
| Grayscale | 256 shades of gray | Documents with photos or illustrations | Smaller than color |
| Black & White (Binary) | Pure black + pure white only | Text-only documents, line art | Much smaller |
| Monochrome | Same as black & white | Maximum ink savings, fax-quality | Smallest possible |
Grayscale converts each pixel to its luminance value, preserving smooth gradients and photographic detail in 256 shades. Photos still look like photos, just without color.
Black and white (also called binary or 1-bit) converts everything to either pure black or pure white using a threshold. Text looks sharp, but photos become harsh, high-contrast silhouettes. This mode produces the smallest files and uses the least ink. To preview a page in grayscale or pure black and white, open a JPG of it in our grayscale image tool.
Rule of thumb: Use grayscale if your document contains any photos, charts, or illustrations. Use black and white only for pure text documents and simple line drawings.
When to Use Each Mode
Grayscale: Documents with Images
Annual reports, brochures, presentations with photos, medical records with imaging, and any document where photo detail matters. Grayscale preserves the visual information while eliminating color.
Black & White: Text-Only Documents
Contracts, legal filings, text-heavy reports, forms, and invoices. Black and white produces the crispest text rendering and the smallest file sizes. It is also the preferred mode for faxing and OCR processing.
File Size Savings
| Mode | A4 page at 300 DPI, uncompressed | Savings |
|---|---|---|
| Color (RGB, 24-bit) | 26.1 MB | — |
| Grayscale (8-bit) | 8.7 MB | 67% less |
| Black & white (1-bit) | 1.1 MB | 96% less |
Ink Cost Savings
On most printers, grayscale printing uses only the black cartridge, so the color cartridges are not touched. How much you save depends on your printer and on how much color the pages had. To estimate it:
- Find the cost per page of your black and color cartridges on the box or the manufacturer’s page.
- Savings = pages × (color cost per page − black cost per page).
- Example: 500 pages a month with a 6-cent difference per page saves $30 a month, or $360 a year.