A color PDF printing in black and white is almost always a printer setting issue rather than a problem with the file. The PDF itself contains color information โ it just isn't reaching the printer in a way that triggers color output. Here's where to look.
Check the Print Dialog Settings
Open the print dialog and look for a color setting before doing anything else. In Adobe Reader: File โ Print โ click Properties or Printer Settings, then find the Color option and make sure it's set to Color rather than Black and White or Grayscale. In Chrome: the print dialog has a Color dropdown directly visible. In Preview on Mac: look under Color Mode in the print options.
This is the fix in the majority of cases. Office printers in particular often default to black and white to save color ink, and whoever set up the printer may have made grayscale the default for all users. Changing it in the print dialog overrides the default for that specific print job.
Printer Driver Default Settings
If you want to change the default permanently so you don't have to switch it every time, you need to change the printer driver settings rather than the in-app print dialog. On Windows: go to Control Panel โ Devices and Printers, right-click your printer, select Printing Preferences, and change the color setting there. On Mac: go to System Settings โ Printers & Scanners, select the printer, click Options & Supplies, and look for a default color mode option.
On a shared office printer, this setting may be locked by the IT department to enforce black-and-white printing as a cost control measure. If that's the case, you won't be able to change it at the driver level โ you'd need to ask IT to allow color printing for your account or use a different printer.
The PDF Might Actually Be Grayscale
Less common but worth checking: the PDF itself may have been exported in grayscale. Some export workflows โ particularly from Word when the document was set up for black-and-white printing, or from design software with a specific output intent โ produce a PDF where all color information has been converted to gray values. In this case the printer is doing exactly what it should; the color was removed before it got there.
A quick way to check: open the PDF and zoom into an area that should be colored. If it looks gray on screen too, the file is grayscale. If it looks correct on screen but prints gray, the printer settings are the issue. If you created the document yourself, check the export settings for a color space or output intent option and re-export in RGB or CMYK.
Low Ink Triggering Grayscale Mode
Some printers automatically switch to grayscale when one or more color ink cartridges are low or empty. The printer can't produce accurate color with depleted ink, so it falls back to black ink only. Check the ink levels through the printer software or the control panel display on the printer itself. Replacing low cartridges should restore color output.
A related issue: if cyan, magenta, or yellow ink has dried out in the printhead (common in printers that sit unused for weeks), cleaning the printhead through the printer's maintenance menu can restore color output without replacing cartridges. Most inkjet printers have a built-in printhead cleaning cycle accessible from the printer's settings menu.