Hi @boitumelo d thanks for posting in the community! You can change the display of the units in the editor from cm to pixel which may help you with converting from px to cm. To do this navigate to File > Pages Settings to open the menu.

Use the dropdown in the 'Canvas' section to select a unit of measurement for your document. For more information on the different settings available please take a look at our Adjust Document Settings article from the help center. 
 

Feel free to respond in this thread if you have any questions or make a new post if there's a new topic you'd like to discuss. Hope this helps!