Success by JazE Edutech / Interactive Tool
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A 401(k) is an employer retirement account with matching contributions. Model your match, paycheck split, and long-term growth side by side in this free calculator.
A 401(k) is an employer-sponsored retirement account that automatically invests a percentage of every paycheck — before income tax in a traditional plan — and many employers add a match on top, such as 50 cents per dollar up to 6% of salary. Because a 50% match is an instant 50% gain on the dollars it touches, capturing the full match is the first move the calculator on this page is built to teach.
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Full written guide, sources, and FAQs
See what a 401(k) really pays: split every projected retirement dollar into your deposits, your employer's match, and compounding — then find out how much match money a low contribution leaves behind.
This resource helps readers connect what is a 401k to classroom practice, standards-aware implementation, and responsible next steps for schools and sponsors.
A 401(k) is a retirement account that an employer sponsors as part of its benefits package, named for the section of the U.S. tax code that created it. You choose a percentage of each paycheck to invest, the money moves automatically before it ever reaches your checking account, and in a traditional 401(k) income tax waits until you withdraw in retirement, according to IRS rules.
The feature that makes 401(k)s famous is the employer match. Many companies promise to add their own money when employees save — a typical textbook setup is 50 cents for every dollar you contribute, up to 6% of salary. Pass on that and you are declining compensation you already earned, which is why teachers often call the match free money. Every projected dollar at retirement splits into your deposits, your employer's deposits, and the growth compounding on top of both.
The Free-Money Match Lab is a match-capture console for the question every first paycheck raises: where should the first dollars of saving go? Enter a salary, a contribution percent, and your plan's match formula, and the lab builds a side-by-side projection — your contributions on one track, the employer match on its own track, growth stacked beneath. A match-capture meter shows what share of available employer money your setup grabs, and a left-behind meter shows what a smaller contribution forfeits.
What it does not do: the lab is not a market forecast, a plan administrator, or advice for your situation. It does not know your funds, fees, vesting schedule, or raises, and its output is an illustrative estimate built from the assumptions you type in.
Six inputs drive every projection, and each one maps to a line you can find on a real paycheck or in a plan's summary plan description. Change any input and the split, the meters, and the ending balance update instantly so cause and effect stay visible.
Read the meters before the balance. The match-capture meter is the verdict on every run: 100% means your contribution percent reaches the cap and the plan owes you nothing more, while anything under 100% means earned employer money is going uncollected every single year. The left-behind meter prices that gap, converting each unclaimed match dollar into forfeited employer deposits and the growth those deposits would have carried across your full horizon. Only after the meters clear does the projected balance matter, and it arrives split into three labeled layers: your contributions, the employer match, and growth. Over long horizons the growth layer often grows larger than either deposit layer — that is compounding doing the heavy lifting, the same mechanism explored in the compound interest explorer.
Treat the growth layer as the least trustworthy number. It assumes the same average return every year, while real markets swing, dip, and recover. Read the contribution and match layers as near-certain — they follow directly from your inputs — and read growth as a range. Rerunning the projection at 2%, 6%, and 9% shows how wide that range really is.
Run the lab with a $52,000 salary, a 6% contribution, a 50% match up to 6% of pay, 40 years, and a 6% assumed return. On a $2,000 biweekly paycheck, $120 flows to the 401(k) and the employer adds $60. At an assumed 6% average annual return — purely for illustration — your deposits grow to roughly $483,000 while the match grows to roughly $241,000 beside it, for a combined balance near $724,000.
Now drag the contribution slider from 6% down to 3% and watch the state change: your $120 drops to $60, the match bar shrinks from $60 to $30 per paycheck, and the left-behind meter climbs past $120,000 in match-plus-growth forfeited over 40 years — about $121,000 in this run. The combined ending balance falls from about $724,000 to about $362,000. Halving your own saving halved more than your deposits: it halved the employer's too.
Every estimate above rests on simplifications that are easy to forget. The lab keeps them in plain view; read this list before quoting any number from a run, and treat surprising outputs as a prompt to check the assumptions rather than a forecast.
The lab pairs naturally with the rest of the SuccessEdu library: the compound interest explorer isolates the growth engine this page assumes, the budgeting kit helps a household find the paycheck slice to contribute, and the down-payment kit applies the same long-horizon math to a nearer goal. Teachers can run the scenario above as a one-period demonstration.
This page and its calculator are educational illustrations only. They are not financial, investment, tax, or legal advice, they do not recommend any specific contribution rate, investment, or provider, and they do not predict or guarantee any financial outcome. Figures shown are illustrative estimates built from the assumptions entered. Plan rules, match formulas, limits, and tax treatment vary; consult your plan's summary plan description, the IRS and Department of Labor resources cited below, and a qualified professional before making decisions.
It is a retirement account sponsored by your employer. You pick a percentage of each paycheck to invest, the money moves automatically before you are paid, and in a traditional 401(k) it grows untaxed until retirement, per IRS rules. Many employers add a match on top of your contributions.
A match is a formula written into your plan document, not a bonus you request. A common classroom example is 50 cents per dollar contributed, up to 6% of salary: at a $52,000 salary, contributing $3,120 a year earns a $1,560 match. Contribute less than the cap and the match shrinks right along with you.
The match is employer compensation — money your plan document promises in exchange for contributing — so it is earned pay rather than a gift. It only behaves like free money if you contribute up to the match cap and keep the dollars through the vesting schedule. Contribute less, or leave the job before vesting completes, and part of that pay never becomes yours.
There is no universal number, but one widely taught starting benchmark is to contribute at least enough to receive the full match, since unclaimed match is compensation you forfeit. Beyond that, the right rate depends on your budget, debts, and goals — use the calculator to test rates against your own paycheck.
Vesting decides how much employer money belongs to you if you leave the job. Your own contributions are always yours; the employer match typically vests over a schedule set by the plan, per Department of Labor guidance. Leave before the schedule completes and some of the match may stay behind — the calculator does not model this.
Yes. A 401(k) holds investments whose values rise and fall, and no average-return assumption is a promise. Longer horizons simply give swings more time to balance out, which is why the same contribution looks very different over 5 years versus 40. The constant-return figures on this page are illustrations, not forecasts.
Both are tax-advantaged retirement accounts, but a 401(k) comes through an employer and can include a match, while an IRA is an account you open yourself with lower annual contribution limits. Many savers eventually use both; the rules, limits, and tax treatment differ, so check IRS guidance for current figures.
Eligibility depends on each employer's plan rules, including any rules for part-time workers. Ask for the plan's summary plan description to confirm eligibility — it spells out who can join, the match formula, and the vesting schedule.
Internal Revenue Service
U.S. Department of Labor, Employee Benefits Security Administration
Internal Revenue Service
U.S. Securities and Exchange Commission, Investor.gov
Social Security Administration