How to use the 401(k) calculator
- Enter your current 401(k) balance and your annual salary.
- Enter your contribution as a percent of salary, then the employer match rate and the match cap. For a plan that adds 50 cents per dollar up to 6% of pay, enter 50 and 6.
- Add the expected yearly salary growth, the expected annual return, the number of years you will keep contributing and, if you want today's dollars, an inflation rate. These are example values you should replace with your own assumptions.
- Read the projected balance, how much came from you, your employer and growth. Open More options to compare your contribution with the IRS limit for your age group. The page shows milestone years and the CSV lists every year.
Formula
Your contribution in year y = salary(y) x your percent
Employer match in year y = salary(y) x min(your percent, match cap) x match rate
salary(y) = starting salary x (1 + raise)^(y - 1)
Each month: balance = balance x (1 + return / 12) + (your contribution + match) / 12
Today's dollars = balance / (1 + inflation)^years
Contributions are added at the end of each month, and the salary changes once a year. With a flat salary and no match the result equals the standard future value of a level monthly annuity.
Worked examples
The default case: a $25,000 balance, a $75,000 salary, a 6% contribution, a 50% match on the first 6%, 3% raises, a 6.5% return and 30 years. In year 1 you contribute $4,500 and your employer adds $2,250, so $6,750 goes in. After 30 years the balance is $1,033,429.00, or about $492,679.72 in today's dollars at 2.5% inflation. Of that, $214,089.37 is your contributions, $107,044.69 is match and $687,294.95 is growth.
Level monthly annuity check: contributing 10% of a flat $60,000 salary is $500 a month. At 6% for 10 years with no starting balance and no match, the balance is $81,939.67, which equals 500 x ((1.005^120 - 1) / 0.005).
The cap matters: on a $50,000 salary, contributing 10% with a 50% match up to 4% earns only 2% of salary from your employer, $1,000 a year. Over 20 years at 7% from a $10,000 start the balance is $300,850.72, with $100,000 from you and $20,000 from the match.
How an employer match formula works
A match is usually written as a percent of what you contribute, up to a cap measured as a share of your pay. Under "50% of the first 6%", contributing 6% earns a 3% match and contributing 10% still earns only 3%. Under "100% of the first 3%", contributing 3% earns a 3% match. Enter the match rate and the cap exactly as your plan states them.
Some plans use tiers, such as a full match on the first 3% and a half match on the next 2%. This calculator models one tier. To model a tiered formula, enter the single rate and cap that give the same total match at your contribution level, then check it against your plan documents.
Many plans also apply a vesting schedule, which means you may keep only part of the employer money if you leave early. Vesting is not modeled, so the balance shown assumes you stay long enough to keep all of it.
Contribution limits
The IRS announced that the 2026 limit on employee contributions to a 401(k) is $24,500, with an extra catch-up of $8,000 for people 50 or older and $11,250 instead of $8,000 for ages 60 to 63. This calculator compares your contribution each year with that figure and shows a notice if you go over it. It never reduces your contribution on its own. These numbers were read from the IRS announcement on October 10, 2026 and change from year to year, so confirm the current limit before you change your payroll deferral.
Employer contributions fall under a separate, larger overall cap that this tool does not check. Your payroll system and plan administrator enforce the limits that apply to you.
Reading nominal and real results
A nominal balance is the dollar amount you would see on a statement in the future. A real balance divides that amount by cumulative inflation so you can judge what it might buy in today's terms. Over 30 years at 2.5% inflation, prices roughly double, which is why $1,033,429.00 in future dollars is about $492,679.72 in today's dollars. Use the toggle to put either figure in the headline.
Assumptions and limits
- The return is a single constant annual rate applied monthly (rate / 12). Real markets move up and down, and the order of good and bad years changes outcomes.
- Contributions are made evenly through the year, at the end of each month, and rise only with salary. Bonuses and one-time contributions are not included.
- The match is one tier: a match rate applied to your contribution up to a cap percent of salary. Tiered formulas, true-ups and profit sharing are not modeled.
- Vesting, fees, fund expenses, taxes on withdrawals, early withdrawal penalties, loans and required minimum distributions are not modeled.
- The example return, raise and inflation values are illustrations to replace with your own assumptions, not forecasts or current market data.
- This is a projection for planning, not financial, tax or investment advice.
Frequently asked questions
How much will my 401(k) be worth in 30 years?
It depends on your balance, savings rate, match, raises and the return you assume. With the default example inputs the projection is about $1.03 million in future dollars. Change each input to see how sensitive the result is, especially the return and the number of years.
How do I enter an employer match like 50% up to 6%?
Put 50 in the match rate and 6 in the match cap. The employer then adds 50 cents for each dollar you contribute, counting only contributions up to 6% of your salary. Contributing more than 6% earns no extra match.
Does the calculator stop me from contributing more than the IRS limit?
No. It uses the numbers you enter and shows a notice when your own contribution passes the 2026 IRS limit for your age selection. The limit is informational because it changes every year and the calculator should never silently change your input.
Why show both nominal and today's dollars?
A large future balance can be misleading because prices rise over decades. The real figure divides by inflation so you can compare the result with costs you know today. Choose which one appears in the headline, and both are listed in the results.
Which return should I use?
There is no correct number. Use a conservative figure and a few alternatives, such as a lower and a higher return, to see a range. The default 6.5% is an example only. Returns are not guaranteed and can be negative in any year.