401(k) Calculator
Project your 401(k) balance at retirement from your contributions, the employer match, expected return, and salary growth, including the match as free money.
Assumptions
- Your contribution is a percent of salary, made at the end of each year. Salary grows at the rate you set, so your contribution grows with it: the first year uses your current salary, and the amount steps up each following year, compounding year over year.
- The employer match is the match rate applied to the lesser of your contribution percent and the cap percent, times salary. So the match is capped: contributing more than the cap raises your own contribution but does not increase the match. The match grows with your salary the same way your contribution does.
- The balance at retirement is your current balance compounded forward at the expected return, plus the future value of the growing stream of your contributions and the employer match. The result is split into your total contributions, the total employer match, and investment growth (the ending balance minus your starting balance, your contributions, and the match).
- The expected return is a single constant rate, compounded annually. Investment fees are not modeled, so a real account with fees would grow more slowly.
- Years to retirement is entered directly, not derived from your age, and is treated as a whole number of years.
- The IRS annual contribution limit is not enforced, because it changes each year. Keep your contributions within the current limit.
- Also not modeled: catch-up contributions for those age 50 and over, employer vesting schedules, Social Security or other retirement income, and any change in your return, salary growth, or contribution rate over time.
- Figures are nominal future dollars, not adjusted for inflation, and before any taxes. A traditional 401(k) is taxed as income when you withdraw in retirement, which the calculator does not model. Each result is rounded to the nearest cent.
- This is an estimate for educational purposes only, not financial, legal, or tax advice. Real returns, salary, and contributions vary, and actual fees and taxes will differ. Consult a qualified professional for guidance specific to your situation.
How it works
Your 401(k) grows from three things: the balance you already have, the money you and your employer add each year, and investment returns on all of it.
Each year you contribute a percent of your salary, and your employer adds a match. A common match is “50% up to 6% of salary,” which means the employer matches half of what you put in, but only on the first 6% of salary. The matched fraction of your salary is therefore:
match% = matchRate × min(yourContribution%, cap%)
If you contribute at least the cap, the match is the full matchRate × cap%. If you contribute less,
the match is smaller. Contributing below the cap leaves part of the match on the table.
Because contributions are a percent of a salary that grows over time, they form a growing stream. The balance at retirement is the current balance compounded forward, plus the future value of that growing contribution stream:
balance = currentBalance · (1 + r)^years + growingAnnuity(firstYearContribution, salaryGrowth, r, years)
Worked example
$50,000 balance, $80,000 salary, you contribute 8%, employer matches 50% up to 6%, 7% return, 30 years, salary growing 2% a year:
- Year one you contribute 8% of $80,000 = $6,400. Your salary and contribution grow 2% a year, so the contributions form a growing stream that totals $259,635.71 over 30 years.
- The match is 50% of your contribution, but only up to 6% of salary. Because you put in 8%, above the 6% cap, the match is 3% of salary: year one 3% of $80,000 = $2,400, totaling $97,363.39. That is free money you would not get by saving outside the plan.
- Current balance grows:
50,000 × 1.07^30 = $380,612.75. - The contribution stream grows to $1,020,957.25.
- Balance at retirement = $1,401,570.00, of which $994,570.90 is investment growth.
Notice the cap: contributing 10% instead of 8% would raise your own contributions, but the match would not change, because it is already capped at 6% of salary.
Assumptions and limits
The return is constant and investment fees are not modeled, so a real account with fees grows more slowly. Figures are nominal and before taxes; traditional 401(k) withdrawals are taxed as income in retirement. The IRS annual contribution limit is not enforced here, because it changes every year. Keep your own contributions within the current limit.
Sources
- Standard future-value math for a growing contribution stream.
- IRS guidance on 401(k) contribution limits (verify the current year’s limit).
Frequently asked questions
- How does the employer match work?
- A common match is 50% of your contributions up to 6% of salary. If you contribute at least 6%, the employer adds 3% of your salary. If you contribute less than the cap, the match is smaller. Contributing at least enough to get the full match is close to free money, so it is usually the first thing to do.
- How much should I contribute?
- At a minimum, enough to get the full employer match, since that is an immediate return on your money. Beyond that, more is generally better for retirement, up to the IRS annual limit, which this calculator does not enforce.
- Is the projected balance in today's dollars?
- No, it is nominal. Inflation will reduce what the balance can buy, and traditional 401(k) withdrawals are taxed as income. Treat the figure as a future dollar amount, not today's purchasing power.
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Last reviewed June 2026. For education, not financial advice.