Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Projected ending TSP balance
$677,480
Annual agency contribution
$4,250
Total agency contributions over the period
$85,000
Total your contributions over the period
$170,000
Effective agency match % of salary
5.0%
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How to use this
- 1Enter annual salary ($).
- 2Enter your contribution rate (%).
- 3Enter current tsp balance ($).
- 4Enter years until retirement.
- 5Enter expected annual return (%).
- 6Read your projected ending tsp balance on the right — it updates as you type.
- 7Hit Share to keep the scenario or send it to someone.
About this calculator
The Thrift Savings Plan is the federal government's 401(k)-equivalent, and FERS employees get a meaningful government match on top of their own contributions: automatic 1% of salary regardless of whether you contribute, plus dollar-for-dollar match on the first 3% you contribute, plus 50 cents per dollar on the next 2%, for a maximum 5% agency contribution when you contribute at least 5% yourself. Skipping past that 5% threshold means leaving free money on the table. This calculator projects your TSP balance forward using your contribution rate, salary, expected annual growth, and years remaining, compounding both your contributions and the agency match. It also isolates how much of your ending balance came from the free agency money versus your own contributions and growth, since that comparison is often what motivates people to at least hit the full match.
Worked example
Using the values the calculator loads with:
Inputs
- Annual salary: 85000 $
- Your contribution rate: 10 %
- Current TSP balance: 40000 $
- Years until retirement: 20
- Expected annual return: 7 %
Results
- Projected ending TSP balance: $677,480
- Annual agency contribution: $4,250
- Total agency contributions over the period: $85,000
- Total your contributions over the period: $170,000
- Effective agency match % of salary: 5.0%
What each field means
Inputs
- Annual salary ($)
- The annual salary used in the calculation, measured in $. Starts at 85000 $ so you have a working example on load.
- Your contribution rate (%)
- The your contribution rate used in the calculation, measured in %. Starts at 10 % so you have a working example on load. Accepted range: 0–100 %.
- Current TSP balance ($)
- The current tsp balance used in the calculation, measured in $. Starts at 40000 $ so you have a working example on load.
- Years until retirement
- The years until retirement used in the calculation. Starts at 20 so you have a working example on load. Accepted range: 1–45.
- Expected annual return (%)
- The expected annual return used in the calculation, measured in %. Starts at 7 % so you have a working example on load. Accepted range: 0–15 %.
Results
- Projected ending TSP balance
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Annual agency contribution
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Total agency contributions over the period
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Total your contributions over the period
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Effective agency match % of salary
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
What's the minimum contribution to get the full match?
You need to contribute at least 5% of your salary to capture the full agency match: 1% automatic plus dollar-for-dollar on the first 3% plus 50 cents on the dollar for the next 2%, totaling 5% agency money on top of your own 5%. Contributing less than 5% means giving up part of that free match.
Does the automatic 1% require me to contribute anything?
No, FERS employees receive the automatic 1% agency contribution regardless of whether they personally contribute at all, though you obviously miss the matching portion (worth up to another 4%) if you don't put in your own money.
Should I split contributions between traditional and Roth TSP?
This depends on your expected tax bracket now versus retirement — traditional contributions reduce taxable income today while Roth contributions grow tax-free, and many people split between both to hedge against future tax rate uncertainty. The agency match, however, always goes into the traditional side regardless of your own election.
How realistic is a 7% growth assumption?
It's roughly in line with long-run historical average annual returns for the TSP's C Fund (S&P 500 equivalent) after inflation is not subtracted, but any single-number projection ignores year-to-year volatility and sequence-of-returns risk near retirement, so treat this as a planning estimate, not a guarantee.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). TSP Growth Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/tsp-growth-calculator
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/tsp-growth-calculator" target="_blank" rel="noopener">TSP Growth Calculator — RevenueLab</a> (2026).</p>
Source: [TSP Growth Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/tsp-growth-calculator) (2026).