401(k) Calculator
Project your 401(k) balance at retirement from your salary, contribution rate, employer match, and expected return — with a year-by-year growth schedule.
How to use this calculator
- 1Enter your current age and the age you plan to retire.
- 2Add your current 401(k) balance and your gross annual salary.
- 3Set your contribution as a percentage of pay, then enter your employer's match rate and the salary percentage it is capped at.
- 4Choose an expected annual return — 6–8% is a common long-run assumption for a diversified stock-heavy portfolio.
- 5Read the projected balance, then compare how much of it comes from your money versus investment growth.
How it works
401(k) projection formula
Bₙ = Bₙ₋₁ × (1 + r) + (C + M) × (1 + r/2) C = salary × contribution rate M = min(contribution rate, match limit) × salary × match rate r = expected annual return salaryₙ = salaryₙ₋₁ × (1 + raise)
Each year the existing balance compounds for a full year, while that year's contributions arrive gradually and are credited with about half a year of growth. The employer match is applied only to the portion of your contribution that falls under the match limit, so contributing above the limit adds your money but no extra match.
Worked example
A 35-year-old earning $75,000 with $45,000 saved, contributing 8% with a 50% employer match capped at 6% of pay, at a 7% return and 2% annual raises, reaches roughly $1.16 million by age 65 — of which about $700,000 is investment growth rather than money paid in.
401(k) Calculator: the complete guide
How a 401(k) actually grows
A 401(k) balance is driven by three engines: the money you contribute, the money your employer adds as a match, and the compound return earned on both. Over a short horizon contributions dominate. Over twenty or thirty years the third engine takes over — in the default scenario above, investment growth alone is larger than every dollar contributed by you and your employer combined.
This is why the single most valuable input in the calculator is the number of years. Delaying contributions by five years costs far more than a one-percent difference in return, because the earliest dollars are the ones that compound the longest.
Understanding the employer match
Employer matches are usually quoted as two numbers: a match rate and a limit. "50% up to 6%" means your employer contributes 50 cents for every dollar you contribute, but only on the first 6% of your salary. Contributing 6% earns the full match; contributing 10% earns exactly the same match, because the extra 4% is above the cap.
The match is the highest-return component of the whole plan — a 50% match is an immediate 50% return on that portion of your contribution before any market growth. If your budget only stretches so far, contributing at least up to the match limit is almost always the first priority.
Some employers use a tiered formula such as "100% of the first 3%, then 50% of the next 2%". To model that here, enter the effective blended rate: in that example the employer contributes 4% of salary when you contribute 5%, so an 80% match limited to 5% of salary gives the same result.
Choosing a realistic rate of return
The return assumption is the input people get most wrong. Long-run US stock market returns have averaged roughly 10% nominal before inflation, but a real portfolio pays fund fees, holds some bonds, and experiences sequences of poor years. Most planners model 6–8% nominal for a stock-heavy allocation and 4–5% for a balanced one.
Because this projection is nominal, the final figure is in future dollars. To think in today's purchasing power, subtract your inflation assumption from the return — entering 4% instead of 7% shows roughly what the balance would buy at today's prices with 3% inflation.
What this projection does not include
The IRS sets annual limits on employee deferrals and on total contributions, and both change most years. This calculator does not cap contributions at those limits, so a very high contribution percentage on a high salary can project more than the law allows.
Fund expense ratios and plan administration fees are also excluded. A 0.5% annual fee reduces a 7% return to an effective 6.5%, which over thirty years can cost more than 10% of the final balance — a reason to enter your return net of fees if you know them.
Finally, traditional 401(k) withdrawals are taxed as ordinary income in retirement, so the projected balance is a pre-tax figure. A Roth 401(k) or Roth IRA holds after-tax money and withdraws tax free, which makes the same nominal balance worth more.
Frequently asked questions
How much should I contribute to my 401(k)?
A common target is 15% of gross pay including the employer match. At minimum, contribute enough to earn the full match — that portion is an immediate, guaranteed return that no investment can reliably beat. Raise the contribution percentage above and watch how the retirement balance responds.
Does this calculator apply the IRS contribution limit?
No. It projects whatever contribution rate you enter so you can explore scenarios freely. The IRS caps employee deferrals each year, with an additional catch-up amount from age 50, so check the current limit before setting your actual payroll deduction.
Why is the projected balance so much larger than what I paid in?
Because returns compound on returns. Each year's growth is added to the balance and then earns its own growth the following year. Over thirty years at 7%, a dollar invested today becomes about $7.61 — so the majority of a long-horizon 401(k) balance is growth, not contributions.
Is the result before or after tax?
Before tax. A traditional 401(k) is funded with pre-tax dollars and withdrawals are taxed as ordinary income, so your spendable amount will be lower than the projected balance. Roth 401(k) contributions are made after tax and qualified withdrawals are tax free.
What happens if I stop contributing but leave the money invested?
Set your contribution to 0% and the projection shows growth on the existing balance alone. Comparing that figure with your normal contribution rate is the clearest way to see how much of your future balance depends on continuing to save.