401(k) Calculator

What Is a 401(k) and How Does Employer Matching Work?

A 401(k) is the most widely used retirement savings vehicle in the United States. Named after a section of the tax code — Section 401(k) of the Internal Revenue Code — it is offered by employers to let workers save pre-tax dollars from each paycheck directly into investment accounts. The money goes in before income taxes are calculated, reducing your taxable income in the year you contribute, and grows without being taxed until you withdraw it in retirement.

The employer match is the feature that makes the 401(k) exceptional. When your employer matches contributions, they are adding money to your retirement account on your behalf — essentially paying you extra compensation that only exists if you participate in the plan. The most common match structure is 100% of the first 6% of your salary. If you earn $70,000 and contribute 6% ($4,200), your employer deposits another $4,200 for free. That is a guaranteed 100% return on $4,200 the instant it lands in the account, before the investments do anything at all.

Other employers use partial match structures. A 50% match on the first 6% means contributing 6% of salary earns you a 50% instant return on that contribution amount. Even this is an extraordinary deal — no savings account, bond, or stock index can reliably match a guaranteed 50% return in day one of the investment.

There is one important caveat: vesting. While your own contributions are always 100% yours immediately, employer match dollars are typically subject to a vesting schedule — a timeline that determines how much of the employer contributions you are entitled to keep if you leave the company before becoming fully vested. Cliff vesting means you get 0% if you leave before the cliff date (often three years) and 100% the moment you cross it. Graded vesting gives you an increasing percentage each year — for example, 20% per year over five years, so you are fully vested after five years of service. If you are close to a vesting cliff, that is a factor worth considering when evaluating a job change.

The single most important rule: always contribute at least enough to capture your full employer match. Failing to do so is leaving part of your compensation on the table — part of the total pay package your employer agreed to give you.

How Much Should You Contribute? The 15% Rule Explained

Financial planners most commonly cite 15% of gross income as the savings target for a comfortable retirement — and this figure includes any employer contributions. If your employer matches up to 6% of your salary and you contribute 6%, you are already saving 12% combined. Adding another 3% of your own salary gets you to the 15% guideline with minimal additional sacrifice.

The 15% figure comes from retirement income replacement analysis. Most financial planning models assume you will need roughly 70% to 80% of your pre-retirement income to maintain your lifestyle in retirement. Social Security typically covers 30% to 40% of a middle-income earner's pre-retirement income. That leaves 30% to 50% of pre-retirement income — or 25 to 30 years of spending — for your personal savings to fund. Saving 15% of income starting at age 25 and investing in a diversified portfolio typically achieves this with a comfortable margin.

The earlier you start, the lower your required savings rate. A 22-year-old contributing 10% of income can often retire at 65 with sufficient funds. A 35-year-old starting from zero may need to save 20% or more. The difference is compounding time — every dollar invested at 25 has 40 years to grow at 7% annually, reaching approximately 15 times its original value by age 65. The same dollar invested at 45 only has 20 years to grow, reaching about 3.9 times its original value.

If 15% is not yet achievable: start at whatever rate captures your full employer match and commit to increasing your contribution rate by 1% each time you receive a raise. Most payroll systems allow automatic annual increases. Because the raise and the contribution increase happen simultaneously, your take-home pay does not feel smaller — the increase is invisible.

Worked example: Maria is 28 and earns $55,000. Her employer matches 100% up to 5% of salary. She currently contributes 5% ($2,750/year), and her employer adds $2,750. She increases her own contribution by 1% each year when she gets a raise. By 40, she is contributing 17% and her employer covers another 5%, for a total of 22% — well above the 15% guideline. Because each increase came with a raise, she never noticed a reduction in take-home pay.

Once you hit the IRS limit — $24,500 for 2026 — additional tax-advantaged savings can go to a Roth IRA ($7,500 in 2026), Health Savings Account (if you have a high-deductible health plan), or taxable brokerage account.

How This Calculator Projects Your Balance

This calculator uses monthly compounding to project your 401(k) balance — a more accurate method than annual compounding because most plans invest and compound on a monthly or daily basis. Here is the exact logic the calculator uses:

1. Convert annual return to monthly: a 7% annual return equals a 0.5654% monthly return (calculated as 1.07^(1/12) − 1 = 0.5654%). This monthly rate is used for every compounding step.
2. Calculate each year's contributions: your annual employee contribution is min(salary × contribution%, IRS limit). The employer adds min(salary × contribution%, salary × match cap%) × match rate. Contributions are divided by 12 to get monthly amounts.
3. Apply IRS catch-up limits: once you reach age 50, the employee deferral limit increases to $32,500. Between ages 60 and 63, the SECURE 2.0 Act super catch-up raises it to $35,750.
4. Compound monthly for 12 months: each month, the calculator adds the monthly contribution to the running balance and multiplies by (1 + monthly return). This correctly models the effect of contributions that arrive throughout the year rather than in a single annual lump sum.
5. Grow salary: at the end of each year, salary is multiplied by (1 + salary growth rate) so contributions in year two are based on a higher salary, and so on for all subsequent years.

A concrete worked example using the defaults: age 30, retiring at 67, $60,000 salary, 10% contribution, 100% employer match to 6%, $0 starting balance, 7% return, 3% salary growth.

Year one: monthly employee contribution = $60,000 × 10% / 12 = $500. Employer matches 6% of $60,000 = $3,600 / 12 = $300 per month. Total monthly contribution = $800. After 12 months of 0.5654% monthly compounding: $800 × ((1.005654^12 − 1) / 0.005654) ≈ $9,905.

Year two: salary grows to $61,800, so employee contributes $515/month and employer $309/month ($824 total). The prior year balance of $9,905 earns 7%, and $824/month in new contributions compound through the year. The balance at year-end approaches $20,800.

Repeating this 37 times, with contributions rising every year as salary grows, produces the final projected balance shown in the results panel. The milestone table shows the balance every 5 years so you can see exactly how the compounding accelerates in the later years of the projection.

2026 IRS Contribution Limits and Catch-Up Rules

The IRS adjusts 401(k) contribution limits annually for cost-of-living increases. For 2026, the limits are:

The catch-up contribution for employees aged 50 and older increased to $8,000 for 2026, raising the total limit from $24,500 to $32,500. For employees aged 60 through 63 specifically, the SECURE 2.0 Act introduced a higher catch-up limit of $11,250 — bringing the total limit to $35,750. This "super catch-up" is designed to help workers in their early sixties — a critical window when many people finally have the financial bandwidth to save aggressively before retirement.

The combined limit of $72,000 covers the total of all contributions to a single participant's account from all sources in 2026: employee deferrals, employer matching contributions, employer profit-sharing contributions, and after-tax contributions. Most workers with typical employer matches will not come close to the $72,000 combined cap.

IRA contribution limits for 2026 are separate from 401(k) limits. Contributing the maximum to your 401(k) does not prevent you from contributing to a Roth IRA ($7,500 under 50 / $8,500 for 50 and older) — assuming you are within the Roth IRA income phase-out range ($150,000 for single filers, $236,000 for married filing jointly for 2026).

Historical context: the $24,500 limit for 2026 represents consistent growth since the 401(k) was introduced in 1978. The limit was $7,000 in 1987, $10,500 in 2000, $15,500 in 2008, $19,500 in 2021, and has been climbing $500 to $1,000 per year since. Inflation indexing ensures the real (purchasing-power-adjusted) value of the contribution space stays roughly constant over time.

Traditional vs. Roth 401(k): Which Is Better for You?

The vast majority of employer 401(k) plans now offer both a traditional (pre-tax) and a Roth (after-tax) contribution option. Both use the same $24,500 limit and can receive employer matching contributions. The choice between them comes down to when you pay taxes — now or later — and your expectation of how tax rates will compare between today and retirement.

Traditional 401(k): contributions come out of your paycheck before taxes. If you earn $80,000 and contribute $8,000 to a traditional 401(k), your taxable income for the year is $72,000. This can drop you into a lower federal tax bracket or save you a meaningful amount in state income taxes. The trade-off: every dollar you withdraw in retirement is taxed as ordinary income at whatever rates apply then.

Roth 401(k): contributions are after-tax — you owe income tax on the money before it goes in, so no deduction now. But all qualified withdrawals in retirement — including decades of investment gains — come out completely tax-free.

The math works in the Roth's favor when your tax rate in retirement is equal to or higher than your current rate. For most workers in their 20s and early 30s — who are at the beginning of their career and in lower tax brackets than they will be in their peak earning years — the Roth is especially compelling.

For high earners in their peak earning years who expect lower taxable income in retirement (because Social Security and required minimum distributions are manageable), the traditional 401(k)'s upfront tax deduction may be more valuable.

Many financial planners recommend a split strategy: contribute some to traditional and some to Roth. This creates tax diversification — in retirement, you can choose whether to draw from the taxable traditional account or the tax-free Roth account depending on which is more advantageous in a given year. Tax rates are set by future legislation and are genuinely uncertain; hedging between the two types reduces the risk of guessing wrong.

One advantage the Roth 401(k) gained starting in 2024: required minimum distributions (RMDs). Traditional 401(k) accounts require you to start withdrawing a minimum amount beginning at age 73, whether you need the money or not. The SECURE 2.0 Act eliminated RMDs for Roth 401(k) accounts during the account owner's lifetime — bringing Roth 401(k)s in line with Roth IRAs and making them more powerful for estate planning and tax management in later retirement.

Note: employer contributions to a Roth 401(k) are deposited pre-tax by default and will be taxed upon withdrawal, even if your own contributions are Roth. Starting in 2024, SECURE 2.0 allows employer contributions to go into Roth accounts if the plan and employer elect to offer this — a feature to verify with your plan administrator.

Investing Inside Your 401(k): What to Own

Once you decide how much to contribute, you need to decide what to invest in. Most 401(k) plans offer a limited menu of mutual funds — often 10 to 30 options — managed by institutional fund families. The right allocation depends on your age, risk tolerance, and how involved you want to be in managing your investments.

Target-date funds are the default investment in most plans for good reason. A target-date fund automatically holds a mix of stocks and bonds that grows more conservative as you approach the target year (your expected retirement year). A 30-year-old using a 2060 target-date fund would own approximately 90% stocks and 10% bonds today, shifting gradually to perhaps 50/50 by the target year. Target-date funds require zero management — you set it and forget it, and the allocation adjusts automatically. Expense ratios have fallen dramatically; index-based target-date funds from Fidelity, Vanguard, and Schwab often charge 0.10% to 0.15% per year.

Index funds are the alternative for investors who want to build their own allocation. A three-fund portfolio — a US stock market index fund, an international stock index fund, and a bond index fund — is supported by decades of academic research. The specific allocation between the three is determined by your time horizon and risk tolerance. A common rule of thumb: hold your age in bonds (age 35 → 35% bonds), though many younger investors use a more aggressive approach (100% stocks until age 50, then gradually shifting toward bonds).

Expense ratios matter enormously over decades. A 1% annual fee versus a 0.05% fee seems trivial in any given year, but over 30 years, the high-fee option consumes a substantial fraction of your final balance. If you have a choice between an actively managed fund and an index fund tracking the same asset class, the index fund has historically outperformed the actively managed fund after fees over 10-year-plus horizons in the vast majority of cases.

Rebalancing: if you build your own allocation, rebalance once per year to bring your portfolio back to target percentages. A strong stock market year may push your stock allocation from 70% to 80% — rebalancing sells some stocks and buys bonds, locking in gains and restoring your intended risk level. Target-date funds do this automatically.

Early Withdrawal: Penalties and Exceptions

The 401(k) is designed for retirement, and the IRS imposes a 10% early withdrawal penalty on distributions taken before age 59½ — on top of ordinary income tax. The combined tax burden of federal income tax plus the 10% penalty can consume 30% to 50% of the withdrawal amount, depending on your bracket.

Example: you withdraw $20,000 at age 45. Federal income tax at a 22% rate = $4,400. Early withdrawal penalty = $2,000 (10%). Total cost: $6,400 — 32% of the withdrawal goes to taxes and penalties before you see a dollar. Additionally, you permanently lose the compounding potential of that $20,000.

However, the IRS provides a list of exceptions to the 10% penalty (the income tax still applies in most cases):

• Age 55 rule: if you leave your employer in the year you turn 55 or later and take distributions from that employer's 401(k) — not rolled over to an IRA — no penalty applies. This is a powerful early-retirement tool.
• Substantially Equal Periodic Payments (SEPP / 72(t)): commit to an IRS-approved series of equal annual distributions lasting at least 5 years or until age 59½, whichever is longer. Complex to set up but allows penalty-free early access.
• Disability: permanent and total disability eliminates the 10% penalty.
• Death: distributions to a beneficiary from an inherited 401(k) are penalty-free.
• Qualified domestic relations order (QDRO): distributions pursuant to a QDRO in a divorce are penalty-free.
• Medical expenses: amounts exceeding 7.5% of adjusted gross income.
• SECURE 2.0 emergency withdrawals: starting in 2024, plan participants may withdraw up to $1,000 for personal or family emergencies once per year, penalty-free (with a three-year repayment window).

401(k) loans are another option some plans offer. You can typically borrow up to 50% of your vested balance (maximum $50,000) and repay it over five years with interest — and the interest goes back to yourself. The key risk: if you leave your job while the loan is outstanding, you generally must repay the full balance within 90 days or it is treated as a taxable distribution subject to the 10% penalty.

As a general rule, avoid withdrawing from your 401(k) early whenever possible. The opportunity cost — losing years of tax-deferred compounding — almost always exceeds the perceived benefit of the withdrawal.

Frequently Asked Questions