size of flash memory with Preferences.h instead of EEprom

I would like to use the Preferences.h to store settings for my project.
You made a pretty good description how to read and write but I didn’t find the size how many … data … I can store there.
EEprom: 512k
But with Preferences.h there are several options for the data types so I think the 512k must be calculated according the Data type but is there a additional Flag for the datatype and the position in the EEprom area to be added to the size of the datatype?
Is there  a formular to calculate the available EEprom space?