How it's calculated
The calculator works one year at a time from now until the year before your retirement age, so 30 to 65 is 35 years of contributions (the years you turn 30 through 64). In year y:
Salary S_y = salary · (1 + raise)^(y − 1)
Your contribution Y_y = min(contribution % · S_y, IRS limit for your age that year)
Employer match E_y = match rate · min(Y_y, match limit % · S_y)
Full match F_y = match rate · min(match limit % · S_y, IRS limit for your age)
Match missed = F_y − E_y
Each month (12 times a year), with g = (1 + annual return)^(1/12):
B = B · g growth
B = B − B · expense ratio / 12 fee (skipped if the expense ratio is 0)
B = B + (Y_y + E_y) / 12 contributions at the end of the month
Investment growth = final balance − starting balance − your contributions − employer contributions
2026 IRS limits used (checked 2026-10-19)
- Your elective deferrals: $24,500. This is the limit on what you put in from your pay (pre-tax and Roth 401(k) contributions combined), shared across all your 401(k) and 403(b) plans if you have more than one job.
- Age 50 and over: $8,000 catch-up, so up to $32,500. The IRS applies it if you are 50 or older by December 31.
- Ages 60, 61, 62 and 63: $11,250 catch-up instead of $8,000 (from the SECURE 2.0 Act), so up to $24,500 + $11,250 = $35,750 in the years you turn 60 through 63. From the year you turn 64 the limit returns to $32,500.
- Source: IRS news release IR-2025-111 (Nov. 13, 2025), "401(k) limit increases to $24,500 for 2026, IRA limit increases to $7,500", on IRS.gov.
- Limits are held at 2026 levels; the IRS adjusts them yearly. The projection uses the 2026 figures for every future year, so with salary raises your contributions may hit the cap in later years when the real (higher) future limit would not stop them.
- Not applied, only flagged: the §415(c) limit on total annual additions (your contributions, not counting catch-up, plus employer contributions: $72,000 for 2026) and the §401(a)(17) compensation limit ($360,000 for 2026; a plan can't count pay above it). Both are in IRS Notice 2025-67. If your inputs exceed either in any year, the results show a warning, because the balance shown would then be too high.
Assumptions, stated plainly
- Monthly contributions. Each year's contributions (yours and your employer's) are paid in 12 equal amounts at the end of each month. Employers that match each paycheck may stop matching once you hit the IRS limit early in the year unless the plan does a "true-up"; that isn't modeled.
- Nominal dollars, before taxes. No income taxes, no inflation adjustment, and no difference between traditional and Roth 401(k) money. Balances are in future dollars, which will buy less than today's dollars.
- No vesting. All employer contributions are counted as yours. Many plans make you work a number of years before the match fully vests.
- Returns are not guaranteed. The same return every year, as an effective annual rate. Real returns vary and can be negative.
- One simple match formula (rate × your contributions, up to a % of salary). Multi-tier formulas (for example 100% of the first 3% plus 50% of the next 2%), profit-sharing and automatic employer contributions aren't modeled. The match applies to all your contributions, including catch-up, up to the cap.
- Catch-up contributions are only possible if your plan allows them. No loans, withdrawals or plan fees other than the expense ratio. Year 1 is treated as a full year at 2026 limits.
- Verified two ways: hand-worked examples in our automated tests, and a separate Python program that recomputes thousands of random cases in decimal arithmetic and compares them with this calculator.
Worked examples
1. One year, worked by hand
$100,000 salary, contributing 6% with a 50% match on contributions up to 6% of salary, 0% return, starting from $0. You put in 6% × 100,000 = $6,000.00. Your employer adds 50% × min(6,000, 6% × 100,000) = $3,000.00. Balance after one year: $9,000.00. Load this example
2. Age 30 to 65 on a $60,000 salary
Starting with $25,000.00, a $60,000 salary rising 3% a year, contributing 6% with a 50% match up to 6%, and an assumed 6% return. After 35 years the balance is $1,093,016.34: $217,663.49 from you, $108,831.75 from your employer, $25,000.00 you started with, and $741,521.10 of investment growth. Load this example
3. Leaving match money on the table
Same as example 2 but with an $80,000 salary and a 3% contribution. In year 1 you put in $2,400.00 and your employer adds $1,200.00, but contributing 6% would bring the full $2,400.00 match: you're leaving $1,200.00/yr of match on the table. Over 35 years the 3% plan ends at $792,728.28; at 6% it would be $1,393,304.40. Load this example
4. Catch-up contributions from 55 to 65
Age 55 with $400,000.00 saved and a flat $250,000 salary, aiming to contribute 20% ($50,000.00). The IRS limit caps that at $32,500 in the years you turn 55 to 59, $35,750 at 60 to 63 and $32,500 at 64, for $338,000.00 in total. The 50% match on up to 6% of salary adds $7,500.00 a year. At a 6% return the balance reaches $1,273,397.85. Load this example
5. What a 0.5% expense ratio costs
Example 2 with funds charging 0.5% a year ends at $976,011.87 instead of $1,093,016.34, $117,004.47 less. Fees actually charged were $58,775.08; the rest is growth those fees would have earned. The expense ratio calculator compares two fee levels side by side. Load this example
Frequently asked questions
What is the 401(k) contribution limit for 2026?
$24,500 of your own (elective) contributions. If you're 50 or older by December 31 you can add an $8,000 catch-up, for $32,500. If you turn 60, 61, 62 or 63 during 2026, the catch-up is $11,250 instead, for $35,750. Source: IRS news release IR-2025-111 on IRS.gov. Employer contributions don't count toward these limits.
What does a "50% match up to 6%" mean?
Your employer adds 50 cents for every dollar you contribute, on your contributions up to 6% of your salary. On a $60,000 salary, contributing 6% ($3,600) earns the full match of $1,800, which is 3% of salary. Contributing more than 6% doesn't raise the match; contributing less lowers it.
How much do I need to contribute to get the full match?
At least the match limit, as a percentage of salary (6% in a "50% up to 6%" plan). The calculator warns you if you contribute less and shows how much match you're missing each year. If your plan matches each paycheck and you reach the IRS limit before the end of the year, you may miss the match for the rest of the year unless the plan makes a "true-up" contribution.
Does the employer match count toward the IRS limit?
Not toward the $24,500 limit on your own contributions. Your contributions (not counting catch-up) and your employer's together fall under a separate limit on total annual additions, $72,000 for 2026 (IRS Notice 2025-67). This calculator flags that limit but doesn't apply it.
Does this 401(k) calculator include taxes, inflation or vesting?
No. Results are in nominal (future) dollars before income taxes, and all employer contributions are treated as fully vested. To think in today's dollars, try a lower return, or use the compound interest calculator's inflation setting.
What return should I assume?
Nobody can promise one. It depends on what your 401(k) is invested in, and returns vary a lot from year to year. Trying a cautious, a middle and an optimistic rate shows how much the result depends on it.
Spotted an error?
Accuracy matters more than anything else here. If a number, formula or explanation on this page looks wrong, please email a correction. The email opens with this page's link, including your current inputs, already filled in. What to include in a report.