FERS Annuity Calculator
The Federal Employees Retirement System (FERS) basic annuity is the defined-benefit part of a federal worker's pension. The standard formula multiplies 1 percent by your high-3 average salary by your years of creditable service. Employees who retire at age 62 or older with at least 20 years of service earn a more generous 1.1 percent multiplier on every year. This calculator takes your high-3 salary, years of service, and retirement age, selects the correct multiplier automatically, and shows your estimated annual and monthly basic annuity before survivor elections, age reductions, and cost-of-living adjustments.
FERS basic annuity formula
If age at retirement >= 62 and years >= 20: multiplier = 1.1%
Otherwise: multiplier = 1.0%
Annual annuity = high-3 * (multiplier / 100) * years
Monthly annuity = annual annuity / 12
Income replacement = (annual annuity / high-3) * 100
This is the standard FERS computation. Special provisions for law enforcement officers, firefighters, and air traffic controllers use different multipliers and are not modelled here.
US FERS context
- FERS retirement has three parts: the basic annuity, Social Security, and the Thrift Savings Plan.
- The 1.1 percent multiplier requires both age 62 or older and at least 20 years of service.
- The high-3 is the highest average basic pay over any three consecutive years of service.
- Choosing a survivor annuity reduces the basic annuity by a set percentage.
- FERS annuities receive cost-of-living adjustments, though the formula differs from CSRS.
FERS annuity: frequently asked questions
How is the FERS basic annuity calculated?
The standard FERS formula is 1 percent times your high-3 average salary times your years of creditable service. If you retire at age 62 or older with at least 20 years of service, the multiplier increases to 1.1 percent. This calculator applies the correct multiplier based on your inputs.
What is the high-3 average salary?
It is the highest average basic pay you earned during any three consecutive years of service, usually your final three years. Basic pay generally excludes overtime and bonuses. Enter your high-3 average as a user-editable input.
When does the 1.1 percent multiplier apply?
The 1.1 percent multiplier applies only if you are at least age 62 at separation and have at least 20 years of creditable service. Otherwise the standard 1 percent multiplier is used. The calculator checks both conditions.
Does this include the FERS supplement or Social Security?
No. This estimates only the FERS basic annuity. The special retirement supplement, Social Security benefit, and Thrift Savings Plan are separate components of FERS retirement income and are not included here.
Is this my final pension amount?
It is an estimate before survivor benefit reductions, unpaid deposits or redeposits, age-based reductions for early retirement, and cost-of-living adjustments. Your official estimate comes from the Office of Personnel Management.
Official sources
- U.S. Office of Personnel Management: FERS Information.
- U.S. Office of Personnel Management: OPM home (retirement computation).
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.