OPM Pension Calculator OPM Pension CalculatorEstimate your Federal Employees Retirement System basic annuity. Retirement System FERS – Federal Employees Retirement SystemCSRS – Civil Service Retirement System High-3 Average Salary The average of your highest 36 consecutive months of basic pay. $ Age at Retirement Creditable Service (Years) Creditable Service (Months) Advanced Options Unused Sick Leave (Hours) Spousal Survivor Benefit NoneFull (Maximum)Partial (FERS Only) Calculate FERS Supplement? NoYes (for retirement before age 62) Estimated SS Benefit at Age 62 $ Calculate PensionYour Estimated FERS PensionMonthly Basic Annuity:—Annual Basic Annuity:—Pension Formula:—Total Service (with sick leave):—PLUS FERS Annuity Supplement—(Payable until age 62)