TSP Calculator: Project a Thrift Savings Plan Balance
Project how a Thrift Savings Plan could grow — the retirement plan for federal employees and members of the uniformed services.
Adjust the inputs and select Calculate for a full breakdown.
Year-by-year growth schedule
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Future value | Total contributions | Total interest earned |
|---|---|---|---|
| $40k · $800/mo · 7% · 25yr | $877,074.08 | $280,000.00 | $597,074.08 |
| $0 · $600/mo · 8% · 30yr | $894,215.67 | $216,000.00 | $678,215.67 |
| $150k · $1k/mo · 6% · 20yr | $958,571.57 | $390,000.00 | $568,571.57 |
| $70k · $500/mo · 7% · 15yr | $357,907.42 | $160,000.00 | $197,907.42 |
How This Calculator Works
Enter the current TSP balance, the average annual return you expect, the years until retirement, and your monthly contribution. The calculator compounds the balance monthly and adds each contribution, showing the projected balance and the growth.
The Formula
Future Value with Regular Contributions
P = starting amount, PMT = monthly contribution, r = monthly rate (annual ÷ 12), n = number of months
Worked Example
With $40,000 saved, $800 added monthly, and a 7% average return over 25 years, a TSP reaches about $877,100. Contributions account for $280,000; investment growth supplies the rest.
Key Insight
The TSP's defining advantage is cost: its index funds carry some of the lowest fees of any retirement plan. Over decades, a fee gap of even a fraction of a percent compounds into a meaningful difference in the final balance.
Frequently Asked Questions
What is the Thrift Savings Plan?
The TSP is the employer retirement plan for U.S. federal employees and uniformed-service members. It works like a 401(k), with traditional and Roth options.
Does the agency match contributions?
Many federal employees receive automatic and matching agency contributions. Include the match in the monthly contribution figure, as it grows in the account too.
Why are TSP fees so important?
The TSP's funds are among the cheapest available. Low fees mean more of each year's return stays invested, which compounds into a larger balance over a career.
What return should I assume?
It depends on the funds chosen, from conservative government securities to stock-index funds. A long horizon supports a return near the cited market benchmark.
Traditional or Roth TSP?
Traditional contributions are pre-tax and taxed on withdrawal; Roth contributions are after-tax and withdrawn tax-free. The Roth suits those expecting a similar or higher future tax rate.
Related Calculators
Data Sources & Benchmarks
This calculator draws on 3 independent, dated sources. The starting values for expected annual return are taken from the benchmarks below and refresh whenever the snapshots are updated.
Methodology & Review
The projection compounds the balance monthly at a constant expected return and adds a fixed monthly contribution. It assumes contributions stay within the annual TSP limit and excludes the very low TSP fees.
Written by Ugo Candido · Last updated May 17, 2026.