Convert a PDF to grayscale
A colour PDF made grey, or pure black and white, for printing and submitting.
Drop files here
or click to choose from your deviceAccepted: PDF
One file per runUp to 20 MB per file5 runs per dayFree PDFs end with a small “Made with nouplo.com” lineRemove limits with Pro✓ Works offline
Your files stay on your device
This tool runs entirely in your browser. Nothing is uploaded, nothing is stored, and you can even turn off your internet connection before you start.
Example
Example: a school newsletter checked in grey before the black-and-white copier
fall-newsletter.pdf, four US Letter pages with a navy masthead, a red “Dates to remember” box, blue links, a green sports heading and shaded boxes in yellow and pale blue. It will be run off on the school’s black-and-white copier, and you want to see first how it will look. Settings: Grayscale, 200 dpi.
- Each Letter page, 612 × 792 points, is drawn at 200 dpi as 1700 × 2200 pixels and then made grey.
- Each colour becomes 0.299 × red + 0.587 × green + 0.114 × blue, on a scale from 0 (black) to 255 (white).
- The red heading (92) and the blue links (96) come out almost the same grey, and the yellow and pale-blue boxes are both 215: on paper they look alike, so label them rather than rely on colour.
- The grey pages are saved as JPEG at quality 85 and put back into a PDF with the same page size.
| Colour in the newsletter | RGB | Grey (0–255) |
|---|---|---|
| Navy masthead | 31, 58, 147 | 60 |
| Red “Dates to remember” | 220, 38, 38 | 92 |
| Blue links | 37, 99, 235 | 96 |
| Green sports heading | 22, 163, 74 | 111 |
| Orange | 234, 88, 12 | 123 |
| Yellow shaded box | 253, 224, 71 | 215 |
| Pale-blue shaded box | 191, 219, 254 | 215 |
| Near-black text | 17, 24, 39 | 24 |
fall-newsletter-gray.pdf, 4 pages, as the copier will print them. Its text can no longer be selected, so keep the colour original for the website and the email.
How it works
- Drop a colour PDF onto the box.
- Keep Grayscale, or choose Black and white for pages of text and line drawings.
- Choose the resolution: 200 dpi for most uses, 300 dpi for print work.
- Select Convert to grayscale and download the new PDF.
Frequently asked questions
- Will the text still be selectable?
- No. Each page is redrawn as a grey picture of itself, so its text can no longer be selected or searched. Keeping the text while making every colour grey would mean rewriting each page's drawing instructions, which cannot be done reliably for every PDF. If you need the text afterwards, run the grey PDF through text recognition.
- Why convert to grayscale instead of printing in black?
- The print dialog does it for your own printer. A grey PDF is for when the file itself must be monochrome: a submission that asks for it, a print shop that charges for colour pages, or checking how a document reads without colour.
- Grayscale or black and white?
- Grayscale keeps every shade, which suits photographs and charts. Black and white keeps only ink and paper, choosing the split per page, which makes text and forms crisp and the file small but turns shading into solid black or white.
- Which resolution should I choose?
- 200 dpi suits most uses. A US Letter page becomes 1275 × 1650 pixels at 150 dpi, 1700 × 2200 at 200 dpi and 2550 × 3300 at 300 dpi: the higher, the sharper small print and fine lines come out, and the larger the file.
- Can two colours turn into the same grey?
- Yes. Grey keeps only how light a colour is, worked out as 0.299 × red + 0.587 × green + 0.114 × blue. A strong red (220, 38, 38) and a bright blue (37, 99, 235) come out 92 and 96, nearly the same, so a chart that tells its lines apart by colour alone is worth checking in grey before it is printed.
- Is the PDF uploaded, and what are the free limits?
- It is not uploaded: each page is drawn in your browser. The free plan takes one PDF of up to 20 MB per run, 5 runs a day, and adds a small "Made with nouplo.com" line to the last page. Pro removes the line and the limits.