TSP Calculator
Federal employees and uniformed service members have poured over $800 billion into the Thrift Savings Plan (TSP)–yet many never run a projection to see what their final balance could be. A TSP calculator turns your current balance, contribution rate, and years to retirement into a single, realistic number you can plan against.
Use the calculator below to find out if you’re on pace for the retirement you want.
What Is a TSP and Why You Need a Calculator
The Thrift Savings Plan is a defined‑contribution retirement plan for federal workers and members of the military, similar to a 401(k) in the private sector. Participants choose how much to contribute from each paycheck, and the government provides matching funds (for most FERS employees).
Because your final balance depends on three variables that change over time–contributions, investment returns, and the number of years until you retire–mental math won’t work. A dedicated calculator compounds all three factors and gives you a month‑by‑month or year‑by‑year projection.
Key Terms in the TSP
- Traditional TSP: Contributions reduce your taxable income now; withdrawals in retirement are taxed as ordinary income.
- Roth TSP: Contributions are made with after‑tax dollars, but qualified withdrawals (after age 59½ and five years from the first Roth contribution) are tax‑free.
- FERS match: For employees under the Federal Employees Retirement System, the government automatically contributes 1% of your base pay and matches contributions dollar‑for‑dollar on the first 3% and 50 cents on the dollar for the next 2%.
- Catch‑up contributions: Participants age 50 and older can contribute extra money beyond the standard limit.
How the TSP Calculator Works
The calculator applies the future‑value formulas used by financial planners, broken down into three layers:
Growth of your existing balance:
current_balance × (1 + annual_return) ^ years_until_retirementGrowth of new contributions added each year:
annual_contribution × ((1 + annual_return) ^ years_until_retirement − 1) / annual_returnSum of the two components, rounded to the nearest dollar.
If you select monthly compounding, the annual rate is divided by 12 and the number of periods multiplies by 12, yielding a slightly higher final balance than annual compounding.
What You Need to Enter
- Current TSP balance: The total dollar amount in your account today.
- Annual contribution: The sum you (and your agency or service) expect to contribute per year.
- Years to retirement: The number of full years you plan to keep working and contributing.
- Estimated annual return: A percentage that reflects your expected investment performance.
- Compounding frequency: Monthly, quarterly, or annual–monthly gives the most precise projection.
The calculator above does all the math instantly.
How to Choose a Realistic Rate of Return
Historical data from the TSP’s core funds offers a starting point:
| TSP Fund | 10‑year average annual return (through 2025) |
|---|---|
| G Fund (government securities) | 2.5% |
| F Fund (fixed income) | 3.5% |
| C Fund (common stock, S&P 500) | 12.0% |
| S Fund (small‑cap stocks) | 11.0% |
| I Fund (international stocks) | 7.5% |
| Lifecycle (L) Funds | 6.0% to 9.0% depending on target date |
A diversified portfolio mixing stocks and bonds historically returned 6–8% annually over 20‑year periods.
Adjusting for Inflation
A nominal balance of $1,000,000 in 20 years buys less than $1,000,000 today. To see your purchasing power, subtract an expected inflation rate (typically 2–3%) from your return. For example, an 8% nominal return and 3% inflation yield a real return of about 5%. The calculator does not automatically adjust for inflation, so choose a real rate if you want today’s dollars.
Contribution Limits for 2026
Understanding contribution limits helps you model the maximum possible scenario:
- Under age 50: estimated limit $24,500 per year.
- Age 50 or older: catch‑up allowance of $7,500, raising the limit to $32,000.
These limits apply to combined traditional and Roth TSP contributions. They can change annually with cost‑of‑living adjustments; confirm the current figure on tsp.gov.
Employer Match and Its Effect
If you are a FERS employee, you receive matching contributions on the first 5% of your base pay you contribute. The match stops once you exceed 5%, so many participants choose to contribute at least 5% to receive the full match. Use that combined figure in your annual contribution input to see the true growth.
Interpreting the Calculator Results
A projection is not a promise–it’s a stress test.
- On‑track: The projected balance meets or exceeds your retirement income goal (common benchmarks are 25× your desired annual spending or enough to replace 70–80% of pre‑retirement income when combined with Social Security and FERS pension).
- Shortfall: If the number looks low, increase contributions now. Even an extra 1% of salary per year can add tens of thousands of dollars over a career.
- Surplus: You might consider shifting a portion to a Roth TSP for tax‑free withdrawals or ramping up early.
The calculator provides estimates only and should not replace professional financial advice. Investment returns are never guaranteed.