Tsp Savings Calculator 

A federal employee who starts with $10,000, contributes $500 a month, earns the full FERS agency match on an $80,000 salary, and assumes 6% a year for 20 years ends with $418,143.82. Without the match, the same contributions and return give $264,122.49. That $154,021.33 gap is why this calculator exists: it projects your TSP balance with monthly compounding, computes the FERS match from your salary, checks your pace against the 2026 contribution limit, and prices the match you leave behind if you contribute less than 5% of pay.

Quick Answer

How to use the TSP savings calculator

Enter six numbers, optionally let the tool compute the match, and read the projection. The results stay hidden until you calculate.

1. Enter your current TSP balance: what is in the account today. The example uses $10,000.
2. Enter your monthly contribution: your own money each month. The example uses $500.
3. Set the employer match: type a percent of your contribution, or enter your annual salary and click Use my FERS agency match to fill it. The example has $80,000 of salary and a 66.67% match pre-filled. If you are CSRS, leave the match at 0.
4. Enter the expected annual return: the average return for the whole horizon, or pick a fund from the dropdown to fill a historical-average illustration. The example uses 6%.
5. Enter the years until retirement: how long everything compounds. The example uses 20 years, and the tool refuses anything above 60.
6. Click Calculate: the projected balance appears in large type, with your contributions, agency match, investment growth, estimated monthly income, and growth multiple underneath. Copy or share the result with the buttons in the results box.

Invalid inputs are rejected with a plain message: a blank or zero-or-negative horizon, a horizon above 60 years, and any negative balance, contribution, match, or return. Blank balance, contribution, match, or return fields are treated as zero, exactly as the live tool treats them, so a blank return gives the simple-sum result rather than an error. The FERS button has its own messages: it asks for a monthly contribution first, then for a salary, and refuses zero or negative values for either.

How the TSP savings calculation works

The calculator compounds monthly, because TSP contributions come out of each paycheck. Future value = balance × (1 + i)ⁿ + P × (((1 + i)ⁿ − 1) ÷ i), where i is the monthly return (annual return ÷ 12), n is the number of months, and P is your monthly contribution plus the agency match. The first term grows your existing balance; the second grows every future contribution. If you enter a 0% expected return, the tool skips the compounding formula, which would divide by zero, and simply adds up balance plus contributions.

Worked example, step by step, with the match: monthly rate = 6% ÷ 12 = 0.5%, months = 240, monthly total = $500 + $333.35 of agency money = $833.35. Balance growth = $10,000 × 1.005²⁴⁰ = $33,102.04. Contribution growth = $833.35 × ((1.005²⁴⁰ − 1) ÷ 0.005) = $385,041.78. Projected balance = $418,143.82. Your contributions = $10,000 + ($500 × 240) = $130,000.00. Agency match = $333.35 × 240 = $80,004.00. Investment growth = $418,143.82 − $130,000.00 − $80,004.00 = $208,139.82. Estimated monthly income at the 4% illustration = $418,143.82 × 4% ÷ 12 = $1,393.81 a month. Growth multiple = $418,143.82 ÷ $210,004.00 = 1.99x.

One honest rounding note: the match field holds 66.67%, the two-decimal rounding of the exact 66.6667% that a full 5% agency contribution represents on a $500 monthly contribution from an $80,000 salary. That rounding adds $4 to the agency total over 20 years, $80,004 instead of exactly $80,000. The tool reports what its own rounded field computes, and this page does the same rather than quietly correcting it.

Without the match, the same inputs give a different story: monthly total $500, contribution growth $231,020.45, projected balance $264,122.49, investment growth $134,122.49, estimated monthly income $880.41. The match does not just add $80,004: it adds the growth on that $80,004 as well, which is why the with-match total is $154,021.33 higher, not $80,004 higher.

The FERS agency match, explained

If you are under FERS, the government contributes even when you do not, and matches generously when you do. For every pay period: 1% automatic, whether you contribute or not; dollar-for-dollar on the first 3% of pay you contribute; 50 cents on the dollar on the next 2% of pay you contribute. Contribute at least 5% of your pay and you collect the full match: 4% in matching plus the 1% automatic, for 5% of your pay in agency money. Contribute less and you leave part of it behind, permanently, because the match is calculated per pay period and cannot be caught up later.

The tool prices that gap in dollars when you enter a salary: contributing 3% on a $100,000 salary earns 4% in agency money instead of 5%, about $1,000 a year of free match unclaimed. The TSP matching calculator answers the match question on its own, without any projection; this page takes that match as one input to a full growth projection, which is why the two pages are companions rather than duplicates. Two groups should not use the FERS button at all: CSRS employees, who receive no agency match, and uniformed members not under the Blended Retirement System, who likewise receive no matching. Both should leave the match field at 0 or type their own agency figure.

2026 TSP contribution limits

The IRS sets these every fall, and the tool checks your pace against the headline figure. For 2026, verified at tsp.gov at draft time: elective deferral limit $24,500, covering your traditional and Roth TSP contributions combined, up from $23,500 in 2025. Standard catch-up for age 50 and older: $8,000, for a total of $32,500. Enhanced catch-up for ages 60 to 63 under SECURE 2.0: $11,250, for a total of $35,750. Annual additions limit: $72,000, covering everything from all sources except catch-up contributions. Agency automatic and matching contributions do not count against your elective deferral limit.

Two warnings ride on those numbers. First, if your monthly contribution annualises past $24,500, the tool flags it and reminds you to spread contributions across pay periods: hit the cap early in the year and your contributions stop, and with them your agency match for the rest of the year. Second, starting in 2026, catch-up contributions must be Roth for higher earners whose prior-year FICA wages from their TSP employer exceeded $150,000. Both points are dated to 2026 on purpose: an undated $24,500 would be worse than a dated one, because it would look permanent. Check tsp.gov each January, and treat any limit figure on this page as a 2026 figure until it is refreshed.

Fund return presets and what they are not

Guessing an expected return is where most TSP projections quietly cheat. The fund dropdown fills the return field from each fund’s long-run historical average: G 2.5%, F 4%, C 9%, S 10%, I 7%. These are illustrations, not predictions, and this page deliberately does not repeat a “since 1988” average claim for the C Fund that could not be tied to a primary TSP source at draft time. The preset value is 9%; the claim about what the fund has averaged over any particular window is a different statement, and it is left out rather than dressed up.

Use the presets as a starting point matched to your mix: a stock-heavy mix justifies something in the 6 to 7% range, a G-Fund-heavy mix justifies 2 to 3%. Then run the projection at a lower return as well, because a single steady return for 20 or 30 years is itself a simplification: real returns vary year to year, and a bad sequence early in retirement hurts more than the same bad years late. The 4% income figure deserves the same caution. It divides 4% of the projected balance by 12. It is a planning illustration borrowed from retirement research, not a TSP rule, and it ignores taxes, inflation, and fees.

What this page does not do, and which tool does

This page projects accumulation only. It does not schedule income, lend money, or price a withdrawal. The TSP payout calculator takes a balance you already have and turns it into a level monthly or annual payment over a horizon you choose. The TSP loan calculator prices borrowing against the balance, including the repayable route that a withdrawal is not. The TSP RMD calculator covers the mandatory distributions this projection ignores. The Roth TSP calculator compares Roth against traditional, a tax question this page deliberately sidesteps by showing pre-tax growth that is identical for both. Together they form a journey: save here, then borrow, withdraw, draw income, or satisfy RMDs as the situation requires.

What competing TSP calculators miss

The strongest competitors each cover part of this page and miss a different part. A scenario projector with conservative, base, and optimistic cases and 2026 limits built in beats this page on range, but it asks you to supply the match logic yourself instead of computing it from your salary. A planner-site projection that shows principal plus contributions plus growth and a 4% income figure matches this page’s outputs, but it folds the match into a single combined contribution and never shows you the match you forfeit. A Monte Carlo projector with per-fund returns and a limit-pacing warning is more sophisticated than a single steady return, but it is an app with a signup funnel, not a one-page check. An annual-compounding explainer that walks through balance growth and contribution growth layer by layer is clearer on the formula, but its annual compounding gives a slightly different answer from the monthly compounding TSP paychecks actually produce, and it offers no match auto-fill at all.

The winning moves on this page are the combination no competitor puts together in one free, no-login tool: monthly compounding that matches paycheck timing, a one-click FERS match computed from salary, a 2026 limit check on the annualised pace, a dollar figure for unclaimed match below 5%, and a growth multiple that makes the compounding visible. The honest limits are stated just as plainly: one steady return, pre-tax growth, no inflation adjustment, and 2026 limits that will go stale in January unless refreshed.

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