How to find size of Non serializable object?

public static int GetSizeOfObject(object obj)
{
    object Value = null;
    int size = 0;
    Type type = obj.GetType();
    PropertyInfo[] info = type.GetProperties();
    foreach(PropertyInfo property in info)
    {
        Value = property.GetValue(obj,null);
        unsafe
        {
            size += sizeof(Value);
        }
    }
    return size;
}