How to use the 401(k) calculator
- Current age and retirement age, the calculator simulates every year in between.
- Current 401(k) balance, whatever you have saved in the account today.
- Annual salary, your gross yearly pay, which contributions are based on.
- Your contribution %, the share of your salary you put in each year.
- Employer match rate %, how much of your contribution your employer matches, commonly 50% or 100%.
- Employer match cap %, the maximum percentage of salary eligible for that match.
- Expected annual return %, your assumed average investment growth (7% is a common default).
- Annual salary increase %, optional yearly raise, which lifts future contributions.
Results update instantly as you type. The summary cards show your projected balance at retirement, how much you and your employer each contributed, and how much of the final total came from investment growth. The table below them shows your balance at five-year milestones along the way.
How your 401(k) grows
A 401(k) builds wealth through three forces working together. First, your contributions, money taken from each paycheck before it ever hits your bank account. Second, the employer match, which is essentially free money your company adds on top, usually up to a set percentage of your salary. Third, and most powerful over decades, compound growth: each year your entire balance earns a return, and those returns then earn returns of their own.
This is why starting early matters so much. A dollar invested at age 25 has 40 years to compound; the same dollar invested at 45 has only 20. Because growth builds on itself, the early years quietly do the heaviest lifting. The calculator makes this visible: in a long projection, the "Total investment growth" figure often dwarfs everything you and your employer actually paid in.
Get the full employer match
The single most important move for most savers is contributing at least enough to capture the entire employer match. If your company matches 100% of your contribution up to 4% of salary and you only contribute 2%, you are leaving half of that free money on the table every single year. The calculator flags this for you directly: if your contribution is below the match cap, a callout shows exactly how many dollars a year you are leaving unclaimed. Try setting your contribution rate equal to (or above) the match cap and watch both the callout clear and the employer total jump.
- Match first: always contribute up to the match cap before anything else, it is an instant, guaranteed return.
- Raise it gradually: bumping your contribution by 1% a year is barely noticeable in your paycheck but huge over time.
- Mind the limit: the IRS caps annual employee 401(k) contributions, so very high salaries may hit that ceiling.
- Stay invested: the projected growth only happens if you leave the money invested through ups and downs.
Frequently asked questions
How does the calculator project my balance?
It steps through each year from your current age to your retirement age, adding your contribution and the employer match, then growing the whole balance by your expected annual return.
How is the employer match calculated?
The calculator takes the smaller of your contribution rate and the match cap, then applies your employer's match rate to it. For example, a 100% match up to 4% of salary means contributing 4% or more gets you the full 4% match; contributing 2% only gets you a 2% match. A 50% match up to 6% means contributing 6% gets you a 3% match.
What return rate is realistic?
Many people use 6% to 7% as a long-term average for a diversified, stock-heavy 401(k). Real returns swing a lot year to year, so treat the result as an estimate, not a guarantee.
Is my data private?
Yes. Everything is calculated in your browser. None of your numbers are uploaded, saved, or shared.
How does the 401(k) calculator project my balance?
It simulates each year from your current age to retirement. Every year it adds your contribution and your employer match, then grows the total balance by the expected annual return you enter.
How does the employer match work?
Your employer matches a set rate, such as 50% or 100%, of your contribution, up to a cap on your salary. The calculator takes the smaller of your contribution rate and the cap, then applies the match rate, so contributing at least up to the cap captures the full match.
What return rate should I use?
A common long-term assumption for a diversified stock-heavy 401(k) is around 6 to 7 percent average annual return. Lower it for a more conservative estimate, since real returns vary every year.
Is my information saved or uploaded?
No. Every calculation runs entirely in your browser. Nothing you type is sent to a server or stored anywhere.
This tool is for general information only and is not financial advice.
Related: Compound Interest Calculator · Savings Goal Calculator · Loan & Mortgage Calculator