The Rule of 75 Retirement Calculation is a common method used to determine when someone is eligible for retirement benefits. To calculate the retirement date, follow these steps:

1. Enter the birth date of the person in one cell, let's say A1. Make sure the date is formatted as a date and not as text.
2. In another cell, let's say B1, enter the date of hire of the person. Again, make sure the date is formatted as a date.
3. To calculate the years of service, subtract the date of hire from today's date. You can use the following formula in another cell, let's say C1:
   
   Formula:

   =DATEDIF(B1,TODAY(),"y") 

4. Now, use the following formula to calculate the retirement date. Replace "Birthdate" with the cell reference of the birth date (A1 in our example) and "Years of Service" with the cell reference of the years of service (C1 in our example):
   
   Formula:

   =DATE(YEAR(A1)+75-C1,MONTH(A1),DAY(A1))