What this calculator does
See how much your 401(k) could grow by the time you retire. A 401(k) is a retirement savings account you get through work. It grows in three ways: money you put in from each paycheck, money your employer adds (the "match"), and investment growth on the whole balance. Over a career, the growth often ends up bigger than everything you put in. That's why starting early and getting the full match matter so much.
The calculator works it out one year at a time. Each year it raises your salary and takes your chosen percent as your contribution. It caps that at the yearly limit you enter, with an extra "catch-up" amount from age 50. Then it adds the employer match and grows the balance at a steady rate. The same math works for a 403(b) or a similar plan at work. You see the result in future dollars, and in today's dollars after inflation (prices rising over time).
Where it's used
Why this math matters outside the classroom:
- Projecting a balance. Savers estimate a future balance by growing last year's total by the assumed return and then adding this year's contributions, year after year.
- Reading a match formula. An employer that matches 50% of contributions up to 6% of a $60,000 salary adds $1,800 when the employee puts in $3,600.
- Testing return assumptions. Running the same plan at 5% and at 7% shows how sensitive a long-term projection is to the assumed rate of return.
- Comparing contribution rates. Employees compare saving 6% against 10% of pay to see how the yearly deposits add up over the same number of years.
- Planning for raises. A projection that grows salary by 3% a year also grows each percent-of-pay contribution, so later deposits are larger than early ones.
How to use it
- Enter your age now, the age you plan to retire and how much is in your account today.
- Enter your salary and the percent you put in. Then enter your employer's match: how much they add, and up to what share of your salary.
- Set your yearly raise, the investment return you expect, inflation and this year's contribution limits.
- Set the withdrawal rate to see what yearly and monthly income your savings could give you, in today's dollars.
- Read your projected balance and what it's worth in today's dollars. Below that is where the money came from and a year-by-year table. If you put in less than you need for the full match, the calculator shows the match you're missing.
What the inputs mean
- Employer match
- How much your employer adds for each dollar you put in. "50% of what you put in" means 50 cents for every dollar. A dollar-for-dollar match is 100%.
- Match applies up to
- The match only counts what you put in up to this share of your salary. With a 50% match up to 6%, putting in 6% earns a 3% match. Putting in more doesn't raise the match.
- Yearly investment return
- The average yearly growth you expect, after fund fees. Real returns go up and down from year to year, and some years they're negative.
- Employee contribution limit (2026)
- The most you're allowed to put in yourself each year. The default is the 2026 IRS limit of $24,500. It usually changes every year, so check the current number. The calculator keeps it the same in later years, which errs on the safe side.
- Catch-up allowance at 50+ (2026)
- The extra amount you can add once you turn 50. The default is the 2026 figure of $8,000. Some plans and ages allow different amounts, so check with your plan.
- Inflation
- How fast prices rise each year. Used only for the today's-dollars figures.
- Yearly withdrawal in retirement
- The share of your balance you'd take out in your first year of retirement. It's only used to turn the balance into an income figure. Starting at 4% is a well-known rule of thumb from studies of past markets. It isn't a promise that your money will last.
Formula and method
salaryₜ = salary × (1 + raise)^t yoursₜ = min(contribution % × salaryₜ, limit + catch-up if age ≥ 50) matchₜ = match rate × min(yoursₜ, match cap % × salaryₜ) balanceₜ₊₁ = balanceₜ × (1 + return) + yoursₜ + matchₜ today's dollars = final balance ÷ (1 + inflation)^years yearly income = today's dollars × withdrawal rate match left on the table = full match at the cap − your first-year match
In the formulas, t is the year, counting from now and starting at 0. A small t below a word means "in year t", so salaryₜ is your salary that year. "min" means "the smaller of". "yours" is what you put in, and "match" is what your employer adds.
Each year, your balance first grows by the return you chose. Then that year's money from you and your employer is added at the end of the year. This errs on the safe side, because real paycheck money arrives all year and starts growing sooner.
The employer match is based on what you put in, but only up to the match cap. It doesn't count toward your own limit. The breakdown shows how much of the final balance came from your starting balance, your contributions, the match and investment growth. Those four parts always add up to the total.
Worked example
You're 35, earn $70,000, have $25,000 saved and put in 8%. Your employer matches 50% up to 6% of your salary. You expect 3% raises, a 6% return and 2.5% inflation, and you plan to retire at 65.
- Years of saving: 65 − 35 = 30.
- What you put in the first year: $70,000 × 8% = $5,600. That's under the $24,500 limit.
- First-year match: 50% × the smaller of $5,600 and 6% of $70,000 ($4,200) = $2,100.
- Balance after year 1: $25,000 × 1.06 + $5,600 + $2,100 = $34,200.
- Repeating this for 30 years, with your salary rising, gives about $994,752.65. That's $25,000 starting balance + $266,422.33 from you + $99,908.37 of match + $603,421.95 of growth.
- In today's dollars: $994,752.65 ÷ 1.025^30 ≈ $474,241.05.
- Income at a 4% withdrawal: $474,241.05 × 4% ≈ $18,969.64 a year, or about $1,580.80 a month.
Result: Your projected balance at 65 is about $994,752.65. After 2.5% yearly inflation, that's worth about $474,241.05 in today's dollars. Taking out 4% in the first year gives about $18,969.64 a year, or $1,580.80 a month, in today's money.
Understanding the result
The today's-dollars figure is the better guide to what your money will buy. A big future number can shrink a lot once you count 20 or 30 years of rising prices.
The income figure turns a lump sum into something you can compare with your budget. It's before tax and leaves out Social Security and other income. So treat it as one piece of your retirement planning, not a full plan.
Look at how much of the total came from growth. The earlier money goes in, the longer its growth can build on itself. So a small bump in your percent early on can matter more than a big bump near retirement. Putting in at least enough for the full match means you don't leave free money on the table.
Assumptions and limitations
- The return is the same every year and is added once a year. Your contributions go in at the end of each year.
- Your salary rises by the same percent each year. Your contribution percent and the match formula never change.
- The contribution limits you enter stay the same in later years.
- No taxes, withdrawals, loans or waiting periods before the match is fully yours (called vesting). Fees are only counted if they're already taken out of the return you entered.
- Real markets go up and down. A steady average can't show what a market drop just before you retire would do.
- It doesn't model the overall limit on what you and your employer can add together. Plan-specific catch-up rules and income-based limits aren't included either.
- This is a projection to help you learn and plan. It isn't financial advice or a promise of future value. Taxes on withdrawals depend on your account type and the rules when you take the money out.
Frequently asked questions
Why are the contribution limits inputs instead of fixed numbers?
Because they change. The IRS usually raises them each year for inflation, and catch-up rules can change too. The defaults are the 2026 figures. Replace them with the current ones for your year and plan.
Does the employer match count toward my limit?
No. Your limit only covers money taken out of your own paycheck. The match is added on top. There is a separate, much higher cap on everything going in, but most savers never reach it.
What return should I assume?
Pick a careful long-term average for your mix of investments, after fees. Try a few different returns, such as 4%, 6% and 8%. That shows you a range of outcomes instead of one number.
Does this work for a 403(b)?
Yes. A 403(b) works the same way. Money comes out of your paycheck up to a yearly limit, your employer may add some, and it grows without yearly tax. Enter your plan's match formula and the current limits.
How much retirement income will my 401(k) provide?
A common way to estimate it is to take out a fixed share in your first year, often 4%. After that you adjust the amount for inflation. The calculator applies your chosen rate to the balance in today's dollars. A higher rate gives more income now, but makes running out more likely. That's especially true if markets fall early in your retirement.
What happens if I contribute less than my employer matches?
You give up free money. Say your employer matches 50% up to 6% of a $70,000 salary. Putting in 3% earns a $1,050 match in the first year, but putting in 6% earns $2,100. The calculator shows this gap whenever you're below the match cap.
Is the result before or after tax?
Before tax. Money you take out of a traditional 401(k) is usually taxed as income. Qualified withdrawals from a Roth 401(k) usually aren't. The calculator shows the account balance and leaves taxes out.
How this calculator is checked
Method: Year-by-year future-value recursion with end-of-year contributions: B(t+1) = B(t)(1 + r) + employee + match; employee capped at a user-entered limit plus catch-up from age 50; match = rate × min(employee, cap × salary). The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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