FinanceCalc401(k) & Retirement Calculator
Project a 401(k) out to the day you retire: your contributions growing with your salary, the employer match, the investment growth, and the income the balance supports. The contribution is checked against the real IRS deferral and 415(c) limits, read from a dated dataset at runtime — not a number typed into this page.
How this is calculated
One year at a time, in the order a plan administrator would credit it:
- Your deferral — a percentage of that year's salary (so it grows with the salary growth rate), or a flat dollar amount held constant in nominal terms. Either way it is capped at the elective deferral limit for your age that year: the base limit, plus the age-50 catch-up, plus the larger 60–63 catch-up.
- Employer match — the match rate applied to your deferral, but only up to the stated percentage of salary. Deferring less than that percentage leaves part of the match unearned.
- Section 415(c) — your deferral plus the employer match plus any after-tax money cannot exceed the combined limit. When it binds, the projection removes the excess from the employer side first and then from the deferral, because the elective limit is the one that applies to money from your pay.
- Contribution timing — contributions are credited at the end of each year, so they earn nothing until the following year. Payroll deferral across 26 paychecks earns slightly more than this shows; the difference is small and in your favour.
- Retirement income — the balance at retirement multiplied by your withdrawal rate. That is the first-year figure in nominal dollars, before tax.
- Today's money — the nominal figure discounted by your inflation assumption over the whole accumulation period. It answers a different question: what the money buys.
The limits are held at the current tax year's level in nominal terms for every projected year, because the data file publishes one year at a time. Real limits are indexed upward each year, so holding them flat makes this projection conservative: it can only understate how much room you would have. Returns, salary growth and inflation are assumptions you supply, not forecasts, and no path is a straight line — see the note below on sequence risk.
What this projection assumes
A single 401(k), a single salary that grows at a constant rate, a constant return, and one lump of contributions credited once a year. That is deliberately simple, and it is the simple version of the arithmetic that actually drives the outcome: time in the account, the amount going in, and the return on what is already there.
The honest way to read the result is as a midpoint, not a promise. A 7% return does not arrive as 7% a year; it arrives as a scatter of +22%, −18%, +9%, and the order matters enormously in the last decade before retirement — the same average return can leave you with a materially different balance depending on whether the bad years land early or late. Shift the return input by a point in either direction and watch what happens to the income line; that spread is the real uncertainty in any retirement projection.
Two inputs are worth more attention than they usually get. Salary growth is what makes the deferral line rise: at 3% a year a $85,000 salary is $212,000 thirty years later, so a percentage-of-salary deferral contributes far more in real terms than a flat dollar amount does. And the gap between the return and the inflation rate is what turns a nominal balance into purchasing power.
How the IRS limits bind
This is the part most projection tools get wrong, and it is not a detail. The elective deferral limit is a hard ceiling on the money that can come out of your pay and go in before tax. Entering 35% of a $200,000 salary does not put $70,000 in the account; it puts in the limit and stops. A calculator that ignores the cap will show a balance you can never have.
The limits stack in a specific way, and the order matters:
- The base elective deferral limit — what you can defer from your own pay.
- The age-50 catch-up — an additional amount once you reach 50, on top of the base.
- The 60–63 catch-up — a still larger amount for ages 60 through 63, and it lapses at 64. The projection applies it only in those years, which is exactly why the limit shown can rise and fall across your own timeline.
- The 415(c) combined limit — your deferral plus everything your employer puts in plus after-tax contributions, for the same year. The match is not your money and it never touches your elective limit, but it does count here.
Exceeding the elective limit is not a rounding error to ignore; the excess is an excess deferral that the plan has to correct, normally by April 15 of the following year, or it is taxed once when deferred and again when withdrawn. In practice payroll stops you first — which is precisely why a projection should stop there too.
The limits change on the IRS's schedule, not yours. This page reads them, the tax year, the source notice and the review date out of assets/data/irs-limits.json at page load and prints them under the input form with a link to the source. If that file cannot be read, the page says so and lets you enter the limits by hand rather than quietly falling back to a stale number — the failure mode to watch for is a competitor pre-filling a limit several years out of date.
What the employer match is really worth
The match is the highest guaranteed return on offer to most people, and it is easy to under-rate because it arrives as a formula rather than a rate. A 50%-of-the-first-6% match is not "half of what you put in": it is a 50% immediate return on the portion of your deferral that falls inside the first 6% of salary, and everything above that percentage earns no match at all. Contributing 3% under that formula earns half of the available match; 6% earns all of it; 12% earns exactly what 6% earns.
Two things make the real value larger than it looks. First, matching dollars are invested for the same decades as your own dollars, so on this page's defaults the employer's share compounds into a six-figure number. Second, deferring before tax means the money goes in at your marginal rate and comes out at whatever your rate is in retirement, which is usually lower.
The counterpart is vesting. A match that is not vested is not yours if you leave, and graded schedules commonly take years to reach 100%. Nothing on this page can know your plan's schedule — the projection treats every match dollar as yours. If you are close to leaving, discount the match by your vested percentage before believing the number.
What this page does not know
- Social Security. Not included. Most US retirement income is three-legged: this account, Social Security, and other savings. The Social Security claiming calculator models the second leg — claim age changes that benefit permanently.
- Other accounts. IRA, Roth, taxable brokerage and cash savings are all outside this model. The IRA limit is not part of a 401(k) projection, and a Roth split inside the plan changes the tax treatment, not the accumulation.
- Taxes in retirement. Withdrawals from a traditional 401(k) are ordinary income, and up to 85% of a Social Security benefit can be taxable once other income is present. The income line here is pre-tax. Withdrawals before 59½ normally carry a 10% penalty on top.
- Required distributions. From age 73 (75 for later birth years) the account must distribute a rising fraction each year, whether or not you want the income. A large balance changes the tax picture in retirement.
- Medicare and healthcare. IRMAA surcharges, Part B premiums and the years between retirement and Medicare eligibility are real costs that a balance has to carry.
- Sequence of returns risk. A constant return is convenient; real markets deliver the same average in a different order, and a bad first five years of withdrawals can shorten a plan's life considerably.
- Fees and fund selection. A plan charges what it charges. Subtract the expense ratio from the return input — a 0.5% plan fee on a 7% market return is a 6.5% input.
- Plan-specific rules. A safe-harbour match, a profit-sharing contribution, a vesting schedule, a 401(a)(17) compensation cap of the compensation limit that limits eligible pay, and auto-enrollment defaults all live in your plan document, not in this model.
Frequently asked questions
How much can I contribute to a 401(k) in 2026?
$24,500 of your own pay as an elective deferral, plus a catch-up of $8,000 once you are 50, or $11,250 at ages 60 through 63. Your deferral and your employer's contributions together are capped at $72,000 under section 415(c). Those are the 2026 figures the page reads from its IRS dataset at load; when the November notice lands, the data file changes and so does every figure on this page.
What happens if I contribute more than the limit?
The excess is an excess deferral. The plan has to correct it — usually by returning the money and its earnings to you by April 15 of the following year. If it is not corrected in time you are taxed on the excess when you defer it and again when you withdraw it, with no deduction on the way in. Payroll systems normally stop you first, which is why the practical risk is low and the projection risk is high.
Does the employer match count against my contribution limit?
Not against the elective deferral limit — that ceiling applies only to money from your pay. The match does count toward the 415(c) combined limit for all additions to the account in the same year. That combined limit only binds at very high deferral levels or with an unusually generous match, which is why this page shows a separate line for whether 415(c) is actually doing anything in your case.
Is the employer match really free money?
It is the highest guaranteed return available to most people — a 50% match on the first 6% of salary is a 50% immediate return on that slice, before any investment gain. Contributing less than the percentage the match covers forfeits the rest permanently, because a year of deferral cannot be backfilled. The match dollars then compound for the same decades as your own, which is how $2,550 a year turns into a six-figure share of the balance.
Why is the income in today's dollars so much smaller?
Because a balance decades out is measured in dollars that will have shrunk. At 2.5% inflation over thirty-two years, a dollar of nominal income buys what roughly 45 cents buys today. The today's-money line is the one to build a budget on; the nominal line is the one your statement will eventually print.
Should I include Social Security here?
No — this tool isolates the 401(k) so you can see what your savings rate alone produces. Retirement income is normally three-legged: this account, Social Security and other savings. Model the second leg with the Social Security claiming calculator and add the two.