FERS Retirement Calculator
How This Calculator Works
FERS Basic Annuity:
If age < 62 or years of service < 20:
Annual Annuity = 1.0% x Years of Service x High-3 Average Salary
If age >= 62 and years of service >= 20:
Annual Annuity = 1.1% x Years of Service x High-3 Average Salary
FERS Supplement (until age 62):
Monthly Supplement = (Years of FERS Service / 40) x Social Security Estimate
TSP Monthly Income (4% Rule):
Monthly Income = (Projected TSP Balance x 0.04) / 12The Federal Employees Retirement System (FERS) provides retirement benefits through three components: the FERS Basic Annuity, the Thrift Savings Plan (TSP), and Social Security. This calculator combines all three to give you a comprehensive picture of your projected federal retirement income.
FERS Basic Annuity Calculation
The FERS Basic Annuity is a defined benefit pension based on your years of creditable service and your "high-3" average salary — the highest average basic pay earned during any three consecutive years of service (usually your last three years). The formula is straightforward: multiply 1% by your years of service by your high-3 salary. If you retire at age 62 or later with at least 20 years of service, the multiplier increases to 1.1%, providing a meaningful boost to your annuity.
For example, a federal employee retiring at age 62 with 30 years of service and a high-3 salary of $95,000 would receive: 1.1% x 30 x $95,000 = $31,350 per year, or about $2,613 per month. This annuity is adjusted annually for cost-of-living increases (COLA), though FERS COLAs are slightly less generous than those for CSRS retirees.
The FERS Supplement
The FERS Supplement is an additional benefit paid to eligible retirees who retire before age 62 on an immediate, unreduced annuity. It approximates the Social Security benefit you earned during your federal career and bridges the gap until you become eligible for Social Security at age 62. The supplement is calculated as your estimated Social Security benefit multiplied by the ratio of your years of FERS service to 40 years. The supplement is not adjusted for inflation and ends when you reach age 62, at which point Social Security benefits may begin.
TSP Projections
The Thrift Savings Plan is the federal equivalent of a 401(k). This calculator projects your TSP balance at retirement based on your current balance, monthly contributions, and expected rate of return. It then estimates a sustainable monthly income using the 4% rule — a widely used guideline suggesting you can withdraw 4% of your portfolio annually (adjusted for inflation) with a high probability of your money lasting 30 years.
Putting It All Together
Your total retirement income is the sum of your FERS annuity, FERS supplement (if applicable), TSP withdrawals, and Social Security benefits. The replacement rate — the percentage of your pre-retirement income that these sources replace — is a key metric. Financial planners generally recommend a replacement rate of 70-80% to maintain your standard of living in retirement. If your projected replacement rate falls short, consider increasing TSP contributions, delaying retirement to increase your annuity, or exploring other savings strategies.
Frequently Asked Questions
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What You Should Know
Planning Your Federal Retirement: A Strategic Approach
Federal employees have one of the most comprehensive retirement benefit packages in the country, but maximizing those benefits requires strategic planning that ideally begins years before your target retirement date. The interplay between FERS, TSP, and Social Security creates both opportunities and complexities that deserve careful consideration.
The Power of the 1.1% Multiplier
One of the most significant decisions federal employees face is whether to work until age 62. The 1.1% multiplier available to those who retire at 62 or later with 20+ years of service provides a permanent 10% boost to your annuity. For a career employee with 30 years and a $100,000 high-3, this means an extra $3,000 per year for the rest of your life — potentially $75,000 or more over a 25-year retirement. However, this must be weighed against the value of retiring earlier and having more years of personal freedom.
Maximizing Your TSP
The TSP is often the largest controllable factor in your retirement planning. In 2025, the maximum employee contribution is $23,500 per year ($31,000 if age 50 or older). Combined with the 5% FERS employer match, you could be putting away over $36,500 per year. The earlier you maximize contributions, the more time compound growth has to work. A federal employee who contributes the maximum from age 30 to 62 at a 7% return would accumulate over $2.5 million — providing roughly $8,300 per month using the 4% rule.
Tax Planning in Retirement
Federal retirees face a unique tax planning opportunity. Your FERS annuity is fully taxable, Traditional TSP withdrawals are fully taxable, and Social Security may be partially taxable. But Roth TSP withdrawals are tax-free. By having both Traditional and Roth TSP balances, you can strategically draw from each account to manage your annual tax bracket, potentially saving thousands in taxes over your retirement. Consider converting some Traditional TSP to Roth during lower-income years to reduce future required minimum distributions and create more tax-free income flexibility.