How to use the 401k calculator
- Enter your details: Fill in your current age, planned retirement age, and current salary.
- Set contribution rates: Specify the percentage of salary you contribute, your employer's match rate, and the match cap (for example, 100% match up to 4% of salary).
- Adjust growth assumptions: Enter expected annual salary growth, investment return, and any existing 401k balance.
- Review the results: The tool shows your projected final balance, total contributions, and a year-by-year table.
How the 401k projection works
This 401k calculator simulates each year from your current age to retirement. In each year it takes your salary (grown by your raise rate), caps the pay a plan can count at the 2026 pay limit, and works out what you want to contribute. Your own deferral is capped at the annual limit, plus a catch-up once you reach the catch-up age: the regular amount at 50 to 59 and 64 and over, and the higher amount at 60 to 63. The employer match is a share of your contribution up to a percent-of-pay cap, and employee deferral plus employer money cannot pass the total limit. The balance then grows by the expected return.
employee = min(pay x rate, limit) + min(max(pay x rate - limit, 0), catch-up)
employer = min( min(employee, pay x match cap) x match rate, total limit - min(pay x rate, limit) )
balance = (balance + employee + employer) x (1 + return)
Contributions and growth are applied once a year, at year end, and the age used for catch-up is your age in that year. Real plans contribute every paycheck, so a real balance is usually a little higher. The limits are held flat; the IRS normally raises them every year or two, so a long projection is conservative on that point.
2026 limits used as the defaults
These are the figures from IRS Notice 2025-67 (tax year 2026), published November 13, 2025. They are the defaults in the fields above; change them to model another year.
| Limit | 2026 amount | 2025 amount |
|---|---|---|
| Employee elective deferral (401k, 403b, governmental 457, TSP) | $24,500 | $23,500 |
| Catch-up, age 50 and over | $8,000 | $7,500 |
| Catch-up, ages 60 to 63 (replaces the regular catch-up) | $11,250 | $11,250 |
| Total employee + employer limit, section 415(c) (catch-up excluded) | $72,000 | $70,000 |
| Pay a plan may count, section 401(a)(17) | $360,000 | $350,000 |
Roth versus traditional treatment of the catch-up for higher earners follows separate IRS rules that this calculator does not model.
Practical use cases
Retirement planning: See how increasing your contribution rate by 1% changes your final balance in this 401k calculator. Job offer comparison: Model two employers with different match formulas to compare total compensation. Catch-up strategy: If you are 50 or older, test the impact of making catch-up contributions. Early retirement: Adjust the retirement age to see how many extra years of work affect your savings.
Common mistakes and edge cases
Forgetting the match cap: An employer match of 100% up to 4% of salary means you must contribute at least 4% to get the full match. Ignoring contribution limits: If your salary is high, your percentage contribution may hit the annual limit before the match cap. Over-optimistic returns: A 10% return may overstate results; many planners use a lower figure for a diversified portfolio. Salary growth vs. inflation: The calculator uses nominal growth; real purchasing power depends on inflation.
Worked example
With the defaults (age 30 to 65, $80,000 salary growing 3%, 10% contribution, a 100% match on the first 4% of pay, 7% return, nothing saved yet) the balance at 65 is 2,355,670.62. You contribute 483,696.65 and your employer 193,478.66. The match is worth about $3,200 in year one, which is why contributing at least up to the match cap is the usual first step.
A check on the limits: a 61-year-old earning $200,000 who defers 20% wants $40,000, but is capped at $24,500 plus the $11,250 age 60 to 63 catch-up, so $35,750 goes in, and the 4% match adds $8,000.
Background: 401k basics
A 401k is an employer-sponsored defined-contribution plan. Contributions are made pre-tax (traditional) or after tax (Roth). Employers often match a portion of employee contributions. The IRS sets annual limits on employee deferrals and total contributions. Funds grow tax-deferred until withdrawal, generally without penalty after age 59 and a half. Required minimum distributions begin at age 73 or 75, depending on your birth year. This 401k calculator focuses on the accumulation phase and does not model taxes, withdrawals, or RMDs.
Method and sources
Method: a year-by-year loop. Limits come from IRS Notice 2025-67 (irs.gov newsroom release "401(k) limit increases to $24,500 for 2026" and the Notice itself); the $11,250 age 60 to 63 amount comes from SECURE 2.0 section 109. The IRS publishes new limits each autumn, so this page needs a yearly refresh (next: Notice for 2027, expected late 2026). Not covered: taxes, Roth catch-up rules, vesting schedules, in-plan fees, mid-year raises and the plan's own rules. Estimate only, not financial or tax advice.
Worked examples
| Example | Input | Result |
|---|---|---|
| Typical 30-year-old | Current age: 30; Retirement age: 65; Current annual salary: 80000; Annual salary growth (%): 3; Your contribution (% of salary): 10; Employer match rate (%): 100; Employer match cap (% of salary): 4; Expected annual return (%): 7; Current 401k balance: 0; Annual contribution limit: 24500; Catch-up limit, age 50+: 8000; Catch-up eligibility age: 50 | Final balance: 2,355,670.62; Total employee contributions: 483,696.65; Total employer contributions: 193,478.66; Total contributions: 677,175.32; Years simulated: 35 |
| High earner with max contributions | Current age: 40; Retirement age: 65; Current annual salary: 200000; Annual salary growth (%): 2; Your contribution (% of salary): 15; Employer match rate (%): 50; Employer match cap (% of salary): 6; Expected annual return (%): 6; Current 401k balance: 50000; Annual contribution limit: 24500; Catch-up limit, age 50+: 8000; Catch-up eligibility age: 50 | Final balance: 2,274,331.01; Total employee contributions: 745,500.00; Total employer contributions: 192,181.80; Total contributions: 937,681.80; Years simulated: 25 |
| Late starter with catch-up | Current age: 55; Retirement age: 67; Current annual salary: 100000; Annual salary growth (%): 1; Your contribution (% of salary): 20; Employer match rate (%): 100; Employer match cap (% of salary): 5; Expected annual return (%): 5; Current 401k balance: 100000; Annual contribution limit: 24500; Catch-up limit, age 50+: 8000; Catch-up eligibility age: 50 | Final balance: 618,637.42; Total employee contributions: 253,650.06; Total employer contributions: 63,412.52; Total contributions: 317,062.58; Years simulated: 12 |
FAQ
Does this calculator account for taxes?
No. It projects the nominal account balance before taxes. Traditional 401k withdrawals are taxed as ordinary income; qualified Roth withdrawals are tax-free. For an after-tax estimate, reduce the final balance by your expected tax rate.
What if my employer matches 50% up to 6% of salary?
Set employer match rate to 50 and employer match cap to 6. The calculator will match 50% of your contribution up to 6% of your salary.
Why does my yearly contribution stop rising after I hit the limit?
The annual limit caps your employee contribution. If salary x contribution rate exceeds the limit, the excess is not contributed. Your balance still grows by the investment return. You can raise the limit field if your plan allows more.
How accurate is the year-by-year table?
The table uses the same formulas as the final result, so it is consistent. It assumes contributions and growth happen once per year at year end, which is a simplification.
Can I use this for a solo 401k?
Only roughly. A solo 401k has your employee deferral plus an employer profit-sharing share of up to about 25% of pay (20% of net self-employment earnings for the self-employed). Set the match rate to 100 and the match cap to that percentage, and keep the total limit at $72,000 for 2026 (catch-up on top).
Do the limits include catch-up contributions?
The $24,500 limit does not include catch-up. The $72,000 total limit also excludes catch-up, so a person aged 50 or over can put in up to $80,000 in 2026 ($83,250 at ages 60 to 63) if the plan allows employer money to fill it.
Which year are the limits for and when do they change?
Tax year 2026. The IRS announces the next year's limits each autumn. This calculator holds today's limits flat for future years, which slightly understates what you could save later.
Can I model a Roth 401k?
Yes for the account balance: the contribution math is identical, and the final balance is the Roth balance. The tax difference (pre-tax now versus tax-free later) is not modelled.