Payroll Services

Pay Calculations

To Determine Semi-Monthly Gross Pay

  Step 1 Divide the actual numbers of hours worked by number of available hours in the pay cycle.
  Step 2 Multiply the result in Step 1 by .5 for half a month.
  Step 3 Multiply Step 2 result by the full time salary without differentials.
  Step 4 Repeat Steps 1, 2, 3 for differentials.
  Step 5 Sum the results from Step 3 and Step 4 to determine the gross pay for a semi-monthly pay cycle.


To Determine Hourly Rate of Pay

Step 1: Take monthly full-time salary, including any monthly differential amounts.

Step 2: Divide the sum from Step 1 by 174 to determine the hourly rate of pay.


To Pay Overtime at Time and A Half

Take the hourly rate of pay and multiply by the number of overtime hours to determine the inflated time and a half gross amount of pay due.

See WAC 357-28-240 through 265 for additional definitions about overtime.

To Pay Comp Time at Straight Time

Multiply the hourly rate of pay by the number of straight time hours to determine the amount of pay due.

Comp time is paid at the employees current rate of pay even though the hours are earned previously.


To Pay Sick Leave Cashout at Retirement

Take the accumulated sick leave hours times 0.25.


To Calculate Accumulated Annual Leave Payoff at Separation/Retirement

Take the full-time monthly salary plus any monthly differentials times .0063.

Take this rate and multiply it by the hours of unused leave time.

Why .0063? This figure is provided by the State Office of Financial Management (OFM).

Formula for deriving the annual leave buyout termination factor:

(8 hours)
(1 day)


(365 days – 104 Saturdays and Sundays – 
11 Holidays 12 days of annual leave)

12 months
= 1          
= .0063

To Pay Annual Sick Leave Cashout in January

Multiply unused accumulated hours from last calendar year times the hourly rate of pay times 0.25. (Maximum casis of claim hours to be paid is 96). The accumulated balance cannot fall below 480 hours.


To Calculate the Value of Leave Without Pay (LWOP)

Step 1:

Divide the number of LWOP hours incurred by the number of available hours to be worked in the pay cycle.

Step 2: Multiply the result from Step 1 by .5 for half a month.
Step 3: Multiply Step 2 result by the full-time monthly salary as determined without any differentials.
Step 4: 

Calculate LWOP for shift differential, chair, additional responsibility, etc., as An individual entry using the same formula.

 Standards provided by OFM:

2,088 Hours (avg available work hours in a year)

174 Hours (avg available work hours in a month)


*Leave Without Pay (LWOP) with a BASE means that the total hours reported on the Time/Leave Report do not match the number of available hours to be worked in a pay cycle.

To Determine Staff Months

Divide the number of hours worked in paycycle by the number of available hours to be worked in the paycycle.  Take result times .5 for half a month. Result gives you staff month value for period.  Take staff month value times fulltime monthly rate of pay to determine paycycle gross pay.

Payroll Services, PO Box 641024, Washington State University, Pullman WA 99164-1024, 509-335-9575, Contact Us