Size of A Class (object) in .NET

How to determine if a Class in .NET is big or small? Is it measured on how many it's attributes or fields, datatype of its attributes/fields? or return type of methods? parameters of it's methods? access modifier of its methods, virtual methods? thanks..

 class A
{

  string x { get; set; }
}

class B 
{
  int x { get; set; }
}

in this example if I instantiate class A and B like this

 A objA = new A();
 B objB = new B();

Is class objA the bigger one because it holds an String property and objB holds only an Int? although I didn't set any value to it's property. thanks

EDIT: Just to clarify my question

suppose i have a class

public class Member
{
    public string MainEmpId { get; set; }
    public string EmpId { get; set; }
}

and another class

public class User
{
    public string AccessLevel { get; set; }
    public string DateActivated { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Mi { get; set; }
    public string Password { get; set; }
    public string UserId { get; set; }
    public string UserName { get; set; }
    public string Active { get; set; }
    public string ProviderName { get; set; }        
    public string ContactPerson { get; set; }
    public string Relation { get; set; }
    public string Landline { get; set; }
    public string MobileNo { get; set; }
    public string Complaint { get; set; }
    public string Remarks { get; set; }
    public string Reason { get; set; }
    public string RoomType { get; set; }
}

if I instantiate it like this

  Member A = new Member();
  User B = new User()

is the object A larger than object B? I know it's an odd question but I believe every intantiation of an object eats memory space..