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.
TSP fund options and asset allocation
TSP offers six core fund choices plus Lifecycle (L) target-date funds and Mutual Fund Window (added 2022).
G Fund: government securities; principal protection; historical return ~3-5% annually; functions as cash equivalent. F Fund: U.S. fixed income bond index; tracks Bloomberg US Aggregate Bond Index. C Fund: U.S. large-cap stocks; tracks S&P 500; primary equity growth fund. S Fund: U.S. small/mid-cap; tracks Dow Jones US Completion Total Stock Market Index. I Fund: international developed stocks; tracks MSCI EAFE Index (changing to broader MSCI ACWI ex-USA ex-China ex-Hong Kong in 2024-2025).
L Funds: target-date Lifecycle funds (L Income, L 2025, L 2030, L 2035, L 2040, L 2045, L 2050, L 2055, L 2060, L 2065). Automatically rebalance to more conservative allocation as target date approaches. Default for new hires (auto-enrolled to age-appropriate L fund).
Mutual Fund Window (2022+): access to 5,000 mutual funds at additional cost (~$150 annual fee + transaction fees). Allows international/specialty exposure beyond core funds. Most TSP participants don't need this — core funds at near-zero cost provide diversified exposure.
FERS retirement income — TSP + pension + Social Security
Federal Employees Retirement System (FERS): three-legged retirement income approach. (1) BASIC ANNUITY (PENSION) — 1.0% per year of service × high-3 average salary (1.1% if retired at 62+ with 20+ years service). 30-year career: ~30-33% of high-3 salary as pension. (2) SOCIAL SECURITY — standard SSA benefits. (3) TSP — defined contribution retirement savings.
Pension component provides substantial income foundation — different from private sector where 401(k) is primary retirement income. This allows TSP to be invested more aggressively (longer time horizon, less reliance on TSP for retirement income).
For maximum federal retirement security: contribute 5% to capture full 5% match (1% auto + 4% match) + additional voluntary contributions beyond match up to $23K limit. Combined with pension and Social Security, this produces substantial replacement of pre-retirement income for typical federal career.
Uniformed services under Blended Retirement System (BRS, 2018+): similar TSP match but reduced pension (2% per year vs 2.5% under legacy system). The match in BRS recognizes the reduced pension; soldiers/sailors should aggressively contribute to TSP to capture this match and supplement reduced pension.
TSP key features and limits (2024)
Reference TSP features and limits for federal employees.
| Feature | Value | Notes |
|---|---|---|
| Employee contribution limit | $23,000 | Same as 401(k) |
| Catch-up 50+ | $7,500 | |
| Auto agency contribution | 1% of salary | Even if employee doesn't contribute |
| Full match | 5% of salary (1% auto + 4% match) | On employee contributing 5%+ |
| TSP fund expense ratios | 0.043-0.082% | Lowest-cost retirement plans |
| Vesting (auto contribution) | 3 years | Cliff vesting |
| Vesting (match) | Immediate | Vested on contribution |
| Roth TSP available | Yes | Since 2012 |
TSP's near-zero expense ratios (0.043-0.082%) are among the lowest of any U.S. retirement plan. Over 30 years vs typical 401(k) at 0.5-1.5%, the fee differential adds $200K-$500K to typical federal retiree's TSP balance. Federal employees should NOT roll TSP to IRA at retirement (rollover often increases costs) unless specific reasons justify the change.
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.
When is this calculator unreliable?
When applying civilian rules to uniformed services under Blended Retirement System (different match vesting schedule). Also unreliable when comparing TSP to private 401(k) without recognizing TSP's unique fee advantage — over decades, TSP at 0.043-0.082% expense ratio dramatically outperforms typical 401(k) at 0.5-1.5% on identical investment returns. Federal employees should maximize TSP contributions before allocating to alternatives.
References & Authoritative Sources
- Thrift Savings Plan (TSP) — Official TSP Information · consulted June 1, 2026 · Federal TSP administrator
- U.S. Office of Personnel Management (OPM) — Federal Employee Retirement Information · consulted June 1, 2026 · Federal employee benefits administrator
- Federal Retirement Thrift Investment Board — TSP Annual Performance Report · consulted June 1, 2026 · TSP oversight board
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.
Embed this calculator
Add this calculator to your website for your readers. The embed includes a neutral attribution link to the original CalcDomain page for methodology, updates, and source notes.
Attribution uses rel="nofollow" by default and is included for transparency, not ranking manipulation.
Suggest an improvement
Found a calculation issue, outdated source, unclear assumption, or missing edge case? Send a short note so we can review it.
Methodology & Review
TSP growth uses compound interest with contributions. The calculator returns balance projection. TSP (Thrift Savings Plan) is U.S. federal government employee retirement plan (also available to uniformed services). 2024 limits same as 401(k): $23,000 + $7,500 catch-up. Federal employees get 1% automatic agency contribution + dollar-for-dollar match up to 3% + 50% match on next 2% = up to 5% match total. Among lowest-cost retirement plans in U.S. (expense ratios 0.043-0.082% in 2024). RELIABILITY: Reliable for documented federal employee parameters. Less reliable for uniformed service members under Blended Retirement System (matching contributions vest at 2 years; different from civilian rules). Investment options limited to TSP funds (G, F, C, S, I, plus L Lifecycle funds and 5,000 mutual fund window added 2022).
Reviewed according to the CalcDomain Editorial Policy & Calculator Methodology. We document formulas, edge cases, sources, update dates, and correction paths for calculator pages.
Updated