Just substitute the date field you want in the Let function where you see Get(CurrentDate) or specify a static date using the Date function. Make sure the calculation is set to not store calculation results, calculate when needed or it will only update when the @Date value is modified (e.g. someone changes the date field contents):
--- START ---
[@Date = Get(CurrentDate);
@BDay = DOB];
Year(@BDay) - Case(@Date <
Date(Month(@BDay); Day(@BDay); Year(@Date)); 1; 0) & " Years, "
Month(@BDay) + 12 - Case(Day(@Date) <
Day(@BDay); 1; 0); 12) & " Months, "
Day(@BDay) + Case(Day(@Date) >=
Day(@BDay); 0; Day(@Date -
Day(@BDay); Day(DOB); Day(@Date -
Day(@Date))) & " Days"
--- END ---
Worked like a charm.
Please note that this will not update as time passes if defined as an auto-enter calculation or as a stored calculation field. It would need to be defined in an unstored calculation.