401(k) Calculator

Quick answers

What is a 401(k)?

A 401(k) is an employer-sponsored retirement savings plan in the United States. You choose a percentage of each paycheck to contribute, the money is invested (usually in mutual funds), and it grows tax-advantaged until you take it out in retirement. The name comes from a section of the US tax code. Its two superpowers are automatic, payroll-based saving and — in most plans — an employer match that adds free money on top of what you put in.

This calculator turns the handful of assumptions that actually drive your balance — your salary and how it grows, your contribution rate, the employer match, expected return, fees, and inflation — into a year-by-year projection. It then layers on the parts a basic balance estimate ignores: the 2026 IRS contribution limits and catch-up tiers, how much match you are capturing versus leaving behind, what an early withdrawal would cost, and what your balance could provide as retirement income.

Everything here is an educational projection, not a forecast. Real returns are not constant, markets fall as well as rise, and tax and plan rules are specific to your situation. The value of the tool is in making the trade-offs visible — when you can see that capturing the full match, or trimming a 1% fee, or adding two percentage points to your contribution each move the final number by a concrete amount, planning becomes a set of decisions you can weigh.

How 401(k) employer matching works (and why it’s free money)

An employer match is a contribution your company adds based on what you contribute, up to a limit. The most common shape is a tiered formula such as “100% on the first 3% of pay and 50% on the next 2%.” Read it tier by tier: defer 3% and the employer adds 3%; defer the next 2% and the employer adds another 1%; so deferring 5% earns a 4%-of-salary match. Contribute less than the full threshold and you simply forgo part of that free money.

The match is the single highest-return feature of a 401(k). A dollar-for-dollar match is an immediate 100% return on that slice of your contribution — nothing else in investing reliably does that. That is why the near-universal advice is to contribute at least enough to capture the full match before doing anything else with the money. The maximiser in this tool shows the exact percentage you need, the dollars you are capturing, the dollars you are leaving on the table, and the match per paycheck.

One subtlety trips people up: many plans match per paycheck, not once a year. If you front-load contributions and hit the annual IRS limit early, your deferrals — and the match on the remaining paychecks — can stop for the rest of the year, unless your plan offers a “true-up.” The calculator flags this front-loading risk so you can spread contributions across the year or confirm your plan’s true-up rule.

Traditional 401(k) vs Roth 401(k)

Both account types grow tax-advantaged; the difference is when you pay tax. Traditional 401(k) contributions come out of your pay before tax, lowering your taxable income today, and you pay ordinary income tax when you withdraw in retirement. Roth 401(k) contributions are made with after-tax dollars — no deduction now — but qualified withdrawals in retirement, including all the growth, are tax-free.

The rule of thumb is about your tax rate now versus later. If you expect to be in a higher tax bracket in retirement, paying tax now via a Roth can come out ahead; if you expect a lower bracket, a traditional deduction now may win. Because the future is uncertain, many people split contributions between the two to hedge. Whichever you choose, the combined deferrals count against the single annual limit — choosing Roth does not give you a second bucket.

This calculator projects the ending balance the same way for traditional, Roth, or a blend, because the contribution and growth math is identical — the difference shows up only when you withdraw. Use the contribution-type selector to label your plan, and remember that the after-tax value of a traditional balance is lower than the headline because withdrawals will be taxed, while a Roth balance is closer to its spendable value.

401(k) contribution limits for 2026

For 2026, the employee elective-deferral limit — the most you can put in from your own pay — is $24,500 if you are under 50. At 50 and older you can add a catch-up of $8,000, raising your personal limit to $32,500. A higher “super” catch-up applies specifically at ages 60 to 63, allowing $11,250 extra for a $35,750 total. The combined employee-plus-employer annual-additions limit is $72,000 before catch-up; catch-up contributions sit on top of that, so the effective combined cap is $72,000 plus any catch-up you are eligible for.

Two practical points. First, the employer match does not count against your personal deferral limit, but it does count toward the combined annual-additions limit — high earners with a generous match can occasionally bump into it. Second, the calculator applies the right limit for your age in every projection year and caps your contribution automatically, warning you if your requested amount would exceed it, so you can dial your per-paycheck percentage to land at the limit without going over.

These limits are inflation-indexed and usually change each year, and tax law itself can change. We hold the 2026 figures constant across the projection, which is the conservative choice because real limits tend to rise over time. Always verify the current numbers with the IRS and your plan administrator before maximising your contributions.

What happens if you contribute too much — or max out too early

If your elective deferrals exceed the annual IRS limit, the excess plus any earnings on it generally has to be returned to you and is taxable in the year contributed. If the excess is not corrected by the tax-filing deadline, it can effectively be taxed twice. Over-contributing happens most often when you switch jobs mid-year and contribute to two plans, or when a high per-paycheck percentage pushes you past the cap before December.

A subtler problem is maxing out too early in a plan that matches per paycheck and does not true up. Because the match is calculated each pay period, hitting the deferral limit in, say, October stops both your contributions and the match for November and December. Over a career that lost match can add up to a meaningful sum. The fix is simple: spread contributions evenly so you reach the limit in the final paycheck, or confirm your plan offers a year-end true-up.

The calculator guards against both. It caps your deferral at the age-appropriate IRS limit, flags when you have asked to contribute more than allowed, and raises a front-loading warning when your contribution pace would hit the limit early in a non-true-up plan. Treat those flags as prompts to check the exact rules with your plan administrator.

Vesting, early withdrawals, and required minimum distributions

Vesting determines how much of the employer’s contributions you keep if you leave. Your own contributions are always fully yours. Employer match may vest immediately, all at once after a set period (“cliff” vesting), or gradually over several years (“graded” vesting). Leave before you are fully vested and you forfeit the unvested match. This calculator assumes the match is fully vested, so check your plan’s schedule — it can change what you actually walk away with.

Taking money out before age 59½ is expensive. From a traditional 401(k) you generally owe ordinary income tax plus a 10% early-withdrawal penalty, unless an exception applies — the “rule of 55” if you separate from that employer at 55 or older, a qualifying disability, certain medical or hardship situations, and others. On top of the tax and penalty, you lose decades of potential compounding. The early-withdrawal estimator above quantifies all three: tax, penalty, and lost future value.

At the other end, traditional 401(k)s are subject to required minimum distributions (RMDs) — mandatory annual withdrawals that currently begin at age 73 under present law, based on your balance and life expectancy. Roth 401(k)s are no longer subject to RMDs during the owner’s lifetime under recent rules. This tool focuses on building the balance and a flexible drawdown estimate rather than computing your exact RMD, which is best confirmed with the IRS or a tax professional.

Common 401(k) mistakes — and when this calculator is enough

The most expensive 401(k) mistakes are avoidable. Not contributing enough to get the full match leaves guaranteed money on the table. Ignoring fees lets a seemingly small 1% expense ratio quietly consume a large share of your balance over decades. Cashing out when changing jobs triggers tax, penalty, and lost growth. Reading the headline (nominal) balance as spending power ignores inflation. And front-loading in a non-true-up plan can cost late-year match.

This calculator is built to surface exactly those issues: it shows the match you are leaving behind, the drag from fees in the net-return figure, the cost of an early withdrawal, every future figure also in today’s money, and a front-loading flag. Use it to pressure-test your current setup and to see how a higher contribution, a lower-fee fund, or a few more working years moves the final number.

It is enough for understanding the big levers and framing decisions. It is not enough for the fine print: it cannot model market crashes and sequence-of-returns risk, your full tax situation, vesting schedules, loan provisions, state-specific rules, or future changes to IRS limits and law. For decisions with real consequences, treat the output as a well-informed starting point and consult a qualified, ideally fee-only, financial professional.

The formulas behind the numbers

The projection runs period by period, so salary growth, the two-tier match, the IRS limits, fees, and inflation all apply across the schedule. Each piece uses the formulas below; the assumptions you enter are shown in full on the page and in the downloadable workbook.

Worked example

A 35-year-old earns $100,000 and contributes 6% of salary to a 401(k) with a 50% match up to 6% of pay. They have $25,000 saved, expect a 7% return with 2.5% inflation, and plan to retire at 65 — 30 years away.

Deferring 6% captures the full match here, so the employer adds $3,000 a year — about $90,000 of free money over the 30 years. The projected $1,117,891 is a future figure; in today’s money it is closer to $532,946, and from a traditional 401(k) the spendable amount would be lower still after tax. Change any input above to see your own numbers.

Assumptions & limitations

This calculator does not predict markets and does not guarantee any outcome. It is an educational estimate that assumes a single, constant return and holds the 2026 IRS limits flat. It does not account for every plan rule, tax law, vesting schedule, investment fee, Roth tax treatment, state-specific rule, or future IRS change. In particular it does not model:

Frequently asked questions

How Calculator Matters checks this calculator

• The engine projects accumulation, employer match, and drawdown and is checked against worked examples (3,600+ automated assertions)
• The downloadable Excel workbook is formula-driven and proven cell-by-cell against the engine (10,500+ formula cells, 0 mismatches)
• IRS 2026 limits ($24,500 deferral, $8,000 / $11,250 catch-up, $72,000 annual additions) are stated, applied by age, and sourced to the IRS
• Verdicts and warnings (match left on table, limit exceeded, front-loading risk) are calculated from your numbers — never a hard-coded “healthy” label
• Every future balance is also shown in today’s money, so inflation is never hidden
• Sources are IRS, FINRA, and SEC/Investor.gov references; results are educational estimates with no guaranteed return and no product recommended

Last reviewed: 14 June 2026 · Method: period-by-period accumulation with two-tier match and age-based IRS limits, plus a formula-driven workbook.

Reviewed by Calculator Matters. This is educational information, not financial, tax, or retirement advice, and no income is guaranteed. Found an error? [email protected].

Sources & references

This calculator uses standard 401(k) math and the 2026 IRS limits; the references below are the official sources we cross-check against. External links open in a new tab.

• 401(k) and profit-sharing plan contribution limitsIRS · Primary source for the annual employee deferral and combined annual-additions limits.
• Retirement topics — catch-up contributionsIRS · Official reference for age-50 and higher catch-up contribution rules.
• Tax on early distributionsIRS · Government guidance on the 10% additional tax and its exceptions.
• Retirement plan and IRA required minimum distributions FAQsIRS · Authoritative reference on RMD age and calculation basics.
• 401(k) basicsFINRA · Regulator investor education on how 401(k) plans, match, and vesting work.
• Employer-sponsored plans — investor educationU.S. SEC — Investor.gov · Plain-language government education on saving and investing for retirement.
• How we calculate — methodologyCalculator Matters · Our internal methodology and review process for this calculator.

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