Convert a PDF to grayscale
Every colour becomes its own shade of grey, and the text stays text.
- Nothing is uploaded
- Works offline after first visit
- Open source
- No watermark · limit is your device’s memory; phones hold less
Turns a colour PDF into grayscale for printing or submission, keeping text as text. It is free, needs no account and adds no watermark, and your files are not uploaded: everything runs in your browser on your device. The size limit is your device’s memory, and phones hold less; give the page a short while after one visit to save itself for offline use, and then it works offline.
Done
Open the network tab. Your files never appear in it.
Add files and run the tool to see every request this tab makes.
Your files are processed on this device and never sent to a server. Reload the page to clear everything from memory.
How it works
- Drop one or more PDFs, or tap to pick them.
- Press Convert to grayscale.
- Download the grayscale copies. Pages, text, links and bookmarks are kept.
In your browser, not on a server
pdf-lib (MIT) opens the PDF in your tab and draws one neutral grey rectangle over each page with the PDF Saturation blend mode. Blending keeps the brightness of whatever is underneath and takes the grey’s zero saturation, so every colour, in text, drawings and photos alike, turns into its own shade of grey. Nothing on the page is rewritten or re-rendered, so text stays text. For the same reason the original colour data is still in the file: the page looks and prints grey, but a check that inspects colour spaces may still detect colour.
Compared with upload-based tools: Most online converters rasterise every page to make it grayscale, which uploads your document, makes text unselectable and often makes the file much larger. Here nothing leaves your device, text stays sharp and searchable, and the file grows by a few hundred bytes.
Verify it yourself. Give the page a short while after one visit to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.
Questions
Is my PDF uploaded?
No. The conversion runs in your browser tab, so the document stays on your device, and the page works offline after one visit and a short wait.
Will the text still be selectable?
If the PDF has text, yes. The pages are not turned into pictures. A grey layer that removes colour is placed over each page, so text can still be selected, searched and copied, and it stays sharp at any zoom. A scanned PDF is made of page images with no text layer, so it stays that way unless it was run through OCR.
Why would I need a grayscale PDF?
Some courts, universities, grant portals and print shops ask for documents in black and white, and a grayscale copy shows how a colour chart or slide deck will look on a mono printer before you print it. Office printers set to colour can also charge a colour page for a single blue logo. One caveat for strict checks: the pages look and print grey, but the original colour data stays inside the file, so a system that inspects colour spaces may still flag it. If a portal or print shop rejects the copy, print the PDF to a new PDF in greyscale from your PDF reader, or use a preflight tool.
Do different colours stay distinguishable?
Colours of different brightness become different greys; colours of similar brightness, such as a mid red and a mid green, can end up almost the same grey. Check charts and colour-coded tables in the result before you send it.
Are comments and form fields converted too?
Highlights, sticky notes and form fields are drawn by your PDF reader on top of the page, so they keep their colour. Flatten them into the page first if they must be grey as well.
Does the file get bigger?
Only by a few hundred bytes per document. Nothing is re-rendered, so there are no page images to add, unlike converters that rasterise every page.
More PDF tools
Crop PDF
Cut PDF pages down to what matters: draw the area to keep, or trim the white margins automatically.
Redact PDF
Find a name or number and black it out for good, or draw boxes by hand. The document stays on this device.
File Checksum
Get a file's checksum on your device and compare it with the one the publisher lists.
JSON ↔ CSV
Paste or drop your data, choose a direction and get a table or an array back. What you paste stays on this device.
Popular conversions
Guides
- How to make a PDF black and whiteChoosing black and white when you print only changes the paper. If a portal or a printer wants the file itself in black and white, you need a converted copy.