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 correspond to ~590px at 150 DPI and to ~1180px at 300 DPI.