In order to convert centimeters or inches to pixels, you will also need to know the resolution of your image. In order to obtain good print results, we recommend using a resolution of at least 150 DPI, preferably 300 DPI.
To convert centimeters or inches to pixels, you can use one of the many free tools available online, for example:
For example, 10 cm corresponds to ~590px at 150 DPI and to ~1180px at 300 DPI.
Moreover, Millimeter to pixel conversion equation is:
Pixel = Millimeter * ( Resolution / 25.4 )
e.g. in case of 300 dpi resolution files Pixel = Millimeter * (300 dpi/25.4= 11.81),
so Pixel = Millimeter * 11.81