C# read-only calculated properties, should they be methods?

Question

I have several entities that have calculated fields on them such as TotalCost. Right now I have them all as properties but I\'m wondering if they should actually be methods. Is

Answer 1

If they are a) lightweight and b) have no side effects, I would make them Properties.

Lightweight is a bit fuzzy of course, but the rule of thumb is: If I ever have to worry calling a Property (be it in a loop or anywhere else), it should possibly be a method.