There is a slight difference in the effect types on the dimmer vs the switch. A community member is creating a interactive calculation tool, but you can try this one in the meantime:
https://docs.google.com/spreadsheets/d/1SGJrJHCUtz8AzznWL_mLCTJjjr2U0IpltcUkRr7N_6M/edit?usp=sharing