401(k) Calculator
Result
Final balance
- Total contributions
- 136,000.00
- Employer contributions
- 63,000.00
- Investment earnings
- 522,649.75
Almost every compound growth page has one payer. A 401(k) has two, and the second one is conditional: the employer adds money only because you did, only up to a limit, and only in the proportion the plan document names. That is why a 401(k) calculator cannot be a savings calculator with a bigger number in it. Enter a salary, the deferral percentage of it you route into the plan, and the employer match formula, and this page reports what each payer put in, what the two of them earned together, and the point at which the match limit turns your extra deferral into money nobody matches. On the defaults - a 70,000 salary, a 6% deferral and a 50%-up-to-6% match - the employer contributes 63,000 of its own money over thirty years, and that 63,000 compounds into 213,494.92 of the retirement balance. Raising the deferral to 10% does not move that figure by a cent.
What each deferral level is worth, on a 70,000 salary with a 50%-up-to-6% match
| Deferral (% of salary) | Your contributions | Employer contributions | Balance at 30 years |
|---|---|---|---|
| 0 | 10000 | 0 | 81164.97 |
| 1 | 31000 | 10500 | 187912.44 |
| 2 | 52000 | 21000 | 294659.9 |
| 3 | 73000 | 31500 | 401407.36 |
| 4 | 94000 | 42000 | 508154.82 |
| 5 | 115000 | 52500 | 614902.29 |
| 6 | 136000 | 63000 | 721649.75 |
| 8 | 178000 | 63000 | 863979.7 |
| 10 | 220000 | 63000 | 1006309.65 |
Read the third column downward and the page's main point is visible without arithmetic: it rises in equal 10,500 steps from 0% to 6%, then stops dead. At 6%, 8% and 10% the employer contributes 63,000 - the same number three times - because the min() in the match formula has stopped responding. The second column never stops: 10,000 at a zero deferral (the starting balance alone, with nothing added), then 21,000 more per percentage point up to 6%, and 42,000 per point for the two rows past the cap, since each extra point is entirely yours. Compare the 0% and 6% rows: the same salary and the same plan, and a 640,484.78 difference in the balance. Of that, 126,000 is extra deferral of your own, 63,000 is the employer's contributions, and the remaining 451,484.78 is what those two streams earned - which is why the employer's 63,000 is worth far more than 63,000 by the end.
Seven employer match formulas, all with the same 6% deferral
| Match rate (%) | Matched up to (% of salary) | Employer contributions | Balance at 30 years |
|---|---|---|---|
| 0 | 0 | 0 | 508154.82 |
| 25 | 6 | 31500 | 614902.29 |
| 50 | 3 | 31500 | 614902.29 |
| 50 | 6 | 63000 | 721649.75 |
| 100 | 3 | 63000 | 721649.75 |
| 100 | 6 | 126000 | 935144.67 |
| 100 | 10 | 126000 | 935144.67 |
Three pairs of rows are identical, and the reason is the formula rather than a rounding artefact. The employer pays match rate times min(your deferral, limit), and your deferral here is 6%: so 25% up to 6% and 50% up to 3% both come to 1.5% of salary, 100% up to 3% and 50% up to 6% both come to 3%, and 100% up to 6% and 100% up to 10% both come to 6%. Only the product matters, and only when your deferral reaches both limits - drop the deferral to 4% and the pairs separate, because a 3% limit binds while a 6% limit does not. So 'up to 10%' is worth nothing extra to someone who defers 6%, which is the single most useful thing to check before comparing two job offers' retirement plans.
Formula
Balance = starting balance x (1 + i)^n + (your deferral + employer match) x [((1 + i)^n - 1) / i] where employer match = match rate x min(your deferral percentage, match limit) x salary i = annual return / 100 / 12 n = years x 12
- Starting balance
- What is already in the account before the first deferral. It counts as your money, because it was - that is why it lands in your contributions and not in the employer's
- Salary
- Annual salary. Both contributors are defined as percentages of it, so this one input scales your deferral and the employer match at the same time
- Deferral
- The share of each paycheque you route into the plan. Deferring is what switches the employer match on at all - at zero, the employer's column is exactly zero
- Match rate
- The share of your matched deferral the employer pays. A 50% rate on a 6% deferral means the employer adds 3% of salary
- Match limit
- The most of your salary the employer will match against. Below it every extra percent of deferral buys more match; at and above it, deferring more buys nothing
- i
- Monthly rate - the annual return divided by twelve, not its twelfth root. This is an expected market return, not a posted APY, and the two conventions answer different questions
- n
- Number of monthly deposits - the years times twelve
Use it when an employer match is part of the answer and you want to see the two payers separately: checking whether you are deferring enough to collect the whole match, pricing what a plan change would do, or working out how much of a projected retirement balance you actually paid for yourself. It is also the fastest way to see the shape of a match formula - that the employer's column stops growing at the match limit while yours does not, so the marginal value of deferring more is high below the limit and zero above it. It is not the right page for a plain deposit: a savings account has one payer, no match, and a posted APY rather than a forecast market return, and the compound growth that page models is a promise where this one is an expectation. For an account whose balance can fall, and whose returns can be negative, this is the page.
Worked examples
The defaults, split by who paid
- Monthly rate: 7% / 12 = 0.583333% per month, over 30 x 12 = 360 months. The growth factor is 1.0058333^360 = 8.116497.
- Salary per month: 70,000 / 12 = 5,833.33. Your deferral is 6% of that, so 350.00 a month.
- The employer matches 50% of the first 6% of salary, and you defer exactly 6%, so it adds 3% of salary: 175.00 a month.
- Your 350.00 a month compounds to 426,989.85; the employer's 175.00 compounds to 213,494.92; the starting 10,000 grows to 81,164.97.
- Balance: 81,164.97 + 426,989.85 + 213,494.92 = 721,649.75. Contributed between you: 10,000 + 350 x 360 = 136,000, plus the employer's 63,000.
The employer's 63,000 of contributions is worth 213,494.92 by retirement, because the match compounds on exactly the same terms as your own money. That is the whole reason to collect it: the 3% of salary the employer adds is not a 3% bonus, it is a stream that grows for thirty years. Note also which column the starting balance landed in - it is your money, so it sits in your contributions, and the panel's two contribution figures plus the earnings reconcile to the balance to the cent.
Deferring 10% when the match stops at 6%
- The monthly rate and the 360 periods are unchanged from the default case.
- Your deferral rises to 10% of 5,833.33, which is 583.33 a month.
- The employer matches min(10%, 6%) = 6%, so it still adds 175.00 a month - exactly what it added at a 6% deferral.
- Your stream compounds to 711,649.75 while the employer's stays at 213,494.92.
- Balance: 81,164.97 + 711,649.75 + 213,494.92 = 1,006,309.65.
The employer's two figures are identical to the previous example, digit for digit, because the min() in the formula has stopped responding to your deferral. The extra four percentage points you defer are entirely your own money - the balance rises by 284,659.90, and not one cent of that comes from the match. That does not make the extra deferral a bad idea: it still earns the same return, and it may carry a tax advantage this page deliberately does not model. It does mean the argument for it has to be something other than the match, because the match ran out at 6%.
Deferring nothing
- Your deferral is 0, so your monthly deposit is 0.00.
- The employer matches min(0%, 6%) = 0% of salary, so its deposit is also 0.00.
- Both annuity streams vanish, leaving only the starting balance to compound.
- Balance: 10,000 x 1.0058333^360 = 81,164.97.
This row is why the match is usually described as free money: the 63,000 the employer was willing to add in the default case is still on the table, and none of it is collected. The employer cannot contribute unless you do - the match is defined on account of your deferral - so a plan participant who defers nothing receives nothing, however generous the plan document looks.
A plan that matches 100% up to 6%
- Your deferral stays at 350.00 a month.
- The employer now pays 100% of the first 6%, which is 6% of salary: 350.00 a month, exactly matching you.
- Both streams are equal, so both compound to 426,989.85.
- Balance: 81,164.97 + 426,989.85 + 426,989.85 = 935,144.67.
Doubling the match rate from 50% to 100% raises the employer's total from 63,000 to 126,000 and the balance from 721,649.75 to 935,144.67 - a 213,494.92 difference from a plan-design change the participant does not control. It is also the case where the employer's contributions equal yours exactly, which makes the split easiest to read off a real statement.
A market return of minus 20%
- Monthly rate: -20% / 12 = -1.666667% per month, again over 360 months.
- The growth factor collapses to 0.9833333^360 = 0.002357, so the starting 10,000 shrinks to 23.57.
- The deposit factor is 59.8586, so your 350.00 a month accumulates to 20,950.51 and the employer's 175.00 to 10,475.26.
- Balance: 23.57 + 20,950.51 + 10,475.26 = 31,449.33, against 199,000 contributed between you.
This is the row that separates this page from every deposit page in the same category. A savings balance cannot do this: a posted APY is what the institution pays, and it is not negative. A market return is a forecast, and a sustained minus 20% compounds against you just as ruthlessly as a positive rate compounds for you. The employer's contribution column is still a healthy 63,000 here while the earnings column is negative, which is why the panel keeps those two apart rather than netting them.
Limitations
The salary is held constant for the whole period, and the deferral with it. In reality pay rises, and because both your deferral and the employer match are percentages of salary, a rising salary lifts both. A thirty-year projection on a level salary therefore understates a career that gets raises, and it cannot show a job change, a period of no contributions, or a plan that suspends its match in a bad year. There is a statutory ceiling on elective deferrals, adjusted annually, and this page does not model it. Above that ceiling the excess is not excluded from gross income for the year, so a high deferral percentage on a high salary can run into a limit that has nothing to do with the employer match limit. The dollar figure is set by an annual notice rather than by the regulation that creates the ceiling, so no number is printed here; the same page should be read as uncapped. The employer match limit and the employer match rate are plan-specific, and nothing enforces that a real plan uses the round numbers this page's defaults do. A plan may match per pay period rather than annually, may require a year of service, may exclude bonuses from the salary it matches against, and may change its formula mid-career. Vesting is not modelled. Employer contributions frequently become yours only after a schedule of years, and leaving before it is fully vested forfeits part or all of the employer's column. Every employer figure on this page assumes the money is yours to keep. The return is a single constant rate. Real markets do not return the same percentage every year, and the order of bad and good years changes the outcome even when the average is identical. A negative rate is allowed precisely because a market return is a forecast rather than a promise, but one constant rate is still a simplification of a sequence. Taxes, fees and inflation are absent. Traditional 401(k) contributions are made before income tax and withdrawals are taxed as income, while a Roth treatment reverses that; this page models neither, so every figure is a pre-tax nominal balance. Fund expense ratios, administrative fees, and the fact that a dollar at retirement buys less than a dollar today are all outside the model. This is a United States employer-sponsored arrangement and the page describes it as one. The employer match, the deferral ceiling and the vesting rules all come from that body of law, and the account cannot be opened by someone outside it. Comparable Chinese arrangements are the enterprise annuity and the private pension account, and they do not share these rules - the employer contribution is capped by regulation rather than by a plan document, and the private pension account has no employer contribution at all.
Frequently asked questions
- How much does the employer match actually add?
- On this page's defaults it adds 63,000 of its own money over thirty years, which compounds to 213,494.92 - roughly 30% of the retirement balance. That is a large fraction for a benefit most participants never price. The figure depends on the match rate and the match limit together: 50% up to 6% of salary is 3% of salary paid by the employer, and 100% up to 6% is 6%.
- Should I defer more than the match limit?
- The match is not a reason to, because the employer's contributions stop growing once your deferral reaches the match limit - the page's own table shows the employer's column flat at 63,000 for deferrals of 6%, 8% and 10%. Money deferred above the limit still earns the same return and may carry a tax advantage this page does not model, so there can be a good reason; it just is not the match.
- Why is the return divided by twelve instead of taking a twelfth root?
- Because it is a market return rather than a posted rate. A bank's APY already contains a year of compounding, so recovering a monthly rate from it means taking the twelfth root. An expected market return contains no compounding, so the honest conversion is a plain division. Treating one as the other is a real error in both directions, and the two sibling pages on this site exist to keep them apart.
- My statement splits employer contributions differently from this page. Which is wrong?
- Neither. Under 26 CFR 1.401(k)-1(a)(4)(ii) your own elective deferrals are treated as employer contributions for reporting purposes, so a statement's employer line usually contains your deferral as well as the match. This page splits by who actually paid, so its employer contributions figure is the match alone and its total contributions figure is your own money. The two figures on this page add to the same gross either way.
- Is there a cap on how much I can defer?
- Yes. Elective deferrals above a statutory annual limit are not excluded from gross income for that year, and the limit is adjusted annually - 26 CFR 1.402(g)-1 creates it and a yearly notice sets the amount. The page does not model the ceiling and no dollar figure is printed here, so a deferral percentage large enough to exceed it will overstate the tax-advantaged total.
- Can the balance go down?
- Yes, and the page allows a negative annual return for exactly that reason. The example at minus 20% ends at 31,449.33 against 199,000 contributed. That is the dividing line between this page and the savings pages in the same category: a posted APY is what an institution pays and is never negative, whereas a market return is a forecast, and compound growth against you is as compounding as it is for you.
- Does the employer's money vest immediately?
- Not necessarily, and the page assumes it does. Many plans vest employer contributions on a schedule of years, and leaving before full vesting forfeits part of that column. The employer contributions figure here is what was contributed and grown, not what is yours to take if you leave.
References
- 26 CFR 1.401(k)-1, Definition of a qualified cash or deferred arrangement; paragraph (a)(4)(ii), Treatment of elective contributions as employer contributions, is the rule that a participant's own deferral is reported as an employer contribution — United States, Electronic Code of Federal Regulations (Title 26, current as of 2026)
- 26 CFR 1.401(m)-1, Matching contributions and employee contributions, which states what does and does not count as a matching contribution — United States, Electronic Code of Federal Regulations (Title 26, current as of 2026)
- 26 CFR 1.402(g)-1, Limitation on exclusion for elective deferrals: the excess of an individual's elective deferrals for a taxable year over the applicable limit for the year may not be excluded from gross income — United States, Electronic Code of Federal Regulations (Title 26, current as of 2026)