Printing a PDF in black and white: printer setting or converted file?

You need a PDF on paper and one of three things is in the way: the colour cartridge at home has run dry, the print shop charges more per colour page than per black page, or the teacher has asked for the assignment in grayscale. Meanwhile the document is full of coloured charts, logo headers and blue text.

There are two ways to deal with it, and they work in different places: tell the printer not to use colour when you print, or convert the PDF itself to gray and hand over that file. Which one suits you depends on whose printer the paper comes out of. Below we settle that decision first, then explain a distinction most people miss: grayscale output and pure black-and-white output are not the same thing.

Whose printer will the paper come out of?

The decision hangs on one question. If you are printing on your own printer, with your own hands, the setting in the print window is usually enough and you never need to touch the file. If the document leaves your hands and is printed on someone else's machine, that setting is no longer yours to control: the person at the print shop, the school copy room or the office you email it to opens it with their own settings. At that point the only thing you can rely on is the file itself.

Where is the black and white option in the print window?

The option's name changes with the program and the printer, but you always look for it in the same place: the print window that opens when you press Ctrl and P together (Command and P on a Mac). Check these spots in order.

• PDF open in Chrome or Edge: find the Color line in the print window and choose Black and white. If the line is missing, your printer driver is not reporting the option to the browser; use the "Print using system dialog" link to reach the printer's own window.
• Adobe Acrobat Reader: the print window has a "Print in grayscale (black and white)" checkbox; tick it and watch the small preview turn gray.
• The printer's own settings on Windows: press Properties or Preferences in the print window; the colour choice usually sits on a tab called Paper/Quality or Color.
• Android phone: tap the small arrow at the top of the print screen and set Color to Black & white.
• iPhone: choose Print from the Share button; if your printer supports it, a Black & White switch appears among the options.

Why the printer setting does not always keep its promise

A print setting is a request, not an order. The program passes it to the printer driver and the driver passes it to the printer, and each link in that chain applies it in its own way. Adobe's user forums have carried complaints for years about pages printing in colour even though the grayscale box was ticked. There is an ink issue too: some inkjet printers build gray not from black ink alone but by mixing the colour inks, so a page that looks gray on screen can still draw on the colour cartridge.

Converting the file removes the uncertainty at the start of that chain: once the page holds no colour information, no setting can bring it back. Which ink the printer uses for gray is still up to the printer, though. If you want the colour cartridge left alone entirely, check the manual or the printer's on-screen menu for a black-cartridge-only mode; some models refuse to print at all when a colour cartridge is empty, and no file can fix that.

Grayscale and pure black and white are not the same

Everyday language calls both of them "black and white", but the results are very different. In grayscale every colour becomes a gray somewhere between black and white, depending on how light it is; photos stay photos and charts stay charts. Pure black and white has no in-between tones: every dot is either fully black or fully white. A threshold decides which; anything darker goes black, anything lighter goes white. Classic fax sends pages this way, and it is common for scanned signatures and stamps.

The diagram shows what five familiar colours turn into under each method. The gray values were calculated with the same formula this site's tool uses; the threshold was placed at the midpoint as an example. Notice two things: red and dark green land on almost the same gray, and with a threshold yellow and orange vanish completely. A line marked with a yellow highlighter stays as a pale band in grayscale but leaves no trace at all in pure black and white.

Which one does the tool on this site produce?

The PDF to Grayscale tool produces grayscale output; it does not apply a threshold. It weights each colour by how bright the eye perceives it and reduces it to a gray; text stays as real letters, the page size does not change, and the downloaded file gets "-grayscale" added to the end of its name so it does not get mixed up with the original. If you need a pure black-and-white file, for example because a system only accepts two-tone documents, this tool will not do that job; ask whoever wants the file which format they expect.

For school and print shops, grayscale is almost always the right choice: charts keep their distinctions and faces stay recognisable in photos. The one caveat is light-coloured text. Yellow, light orange or light blue lettering comes out faint once it turns gray, so if your document has any, zoom in on screen after converting and check that it is still readable.

If what you have is not a PDF but a photo or a screenshot, the Black and White photo tool uses the same formula; you still go through the print settings above when you print the result.

Three checks before you hand it over

• Do not delete the colour original: the colours cannot be recovered from the gray copy, and one day you may need them again.
• Read the result line: if some pages were turned into images because of colour gradients, the tool says how many; text on those pages cannot be selected, so zoom in once on any small print.
• Put only the gray file on the USB stick you take to the print shop; with two copies side by side, the clerk may open the colour one.

Frequently asked questions

Can I print a black and white PDF when the colour cartridge is empty?

It depends on the printer. Some models carry on printing with black only, others refuse to print at all. The second case is not a file problem, so converting the PDF to gray will not solve it; check the printer's warning and its manual.

Does a grayscale PDF get smaller?

Usually not by much. Text and drawings keep the same instructions, so the size stays roughly the same; pages that had to be turned into images can even make the file a little bigger. If size is your goal, run it through the PDF compression tool as well.

Can I turn a black and white PDF back into colour?

No. Converting to gray keeps only how light each colour was; which colour became which gray is not stored in the file. If you need the colour version, use the original.

Can I convert a PDF to black and white on my phone?

Yes. The tool runs in your phone's browser too: pick the PDF from the Files app, press the button, and the gray copy lands in your Downloads folder. From there you can print it directly or send it to the print shop.

Will the print shop charge the black and white price for a grayscale PDF?

The shop sets its own prices, and only they can tell you. What converting gives you is certainty that no colour reaches the paper whatever the clerk's settings are, which makes that conversation easier.

Last updated: October 12, 2026