SQL database concerns – Microsoft Q&A

I am currently making the change from ACCESS to SQL database. I am setting up a database and there is one thing that I am unable to confirm.
For my text fields I have selected to use nvarcar(). When setting the value for the max field size (reflected in characters), is the number reflect the max amount of memory that can be used, with a minimum amount of memory set aside for the field? I am using field interchangeably with record, but I am sure that the difference can be easily discerned.
I have concerns about the size setting. I am confused as to exactly how much memory is set aside to an empty nvarcar() field. It is my understanding that the size you fill into the parentheses, nvarcar(250), sets the maximum size of that the field to the value, without effecting the amount of memory set aside.
There are some fields that I want to be nvarcar(MAX). I am especially concerned about the amount of memory that is set aside for this type of field. There will be a lot of them. I don’t mind a memory hog record, if there is a lot of content, but I don’t want to leave a lot of unused memory sitting on the table.