401(k) Calculator
Your pay, your rate, and the match formula
Your result will appear here
Fill in the fields on the left and this updates as you type.
Know what this estimate is based on
- Jurisdiction
- General mathematical model
- Scope and limitations
- Scenario model, not a forecast. Returns, volatility, inflation, fees, and taxes are assumptions and actual investment outcomes can be lower or negative.
- Source links checked
- Jul 30, 2026
Built and regression-tested by Smart Tools Lab. It has not been individually reviewed by a licensed financial, tax, or legal professional.
How to use
- 01
Enter your annual salary and the share of pay you currently contribute.
- 02
Enter the match formula from your plan document as the two numbers it already is: the cents your employer adds per dollar you put in, and the share of pay the match stops at. "50% up to 6%" is 50 cents and 6%.
- 03
Add your age, marginal tax rate and the balance in the plan today.
- 04
Read the match you are leaving behind, the contribution rate that captures all of it, and what that rate costs you per paycheck after the pre-tax break.
Formula
Match captured = min(your contribution, salary × match cap %) × cents matched per dollar. Match forfeited = the match at the cap rate − the match captured. Per-paycheck cost = salary × your rate ÷ pay periods × (1 − marginal rate).
Example
On $85,000 with a 50%-up-to-6% formula: contributing 4% puts in $3,400 and earns $1,700 of match. Contributing 6% would put in $5,100 and earn $2,550 — so 4% leaves $850 on the table. Moving from 4% to 6% costs $1,700 more a year, which at 26 pay periods and a 22% bracket is about $51 more per paycheck for $850 of employer money.
Definitions
- Elective deferral
- What you choose to divert from your own pay into the plan. Capped at $24,500 in 2026, plus an $8,000 catch-up from age 50.
- Match cap
- The share of your pay beyond which the employer stops matching. Contributions above it still shelter income but earn no more match.
- Marginal tax rate
- The rate your last dollar of income is taxed at — what a pre-tax deferral actually saves you.
Good to know
The match is the only guaranteed return in the account
A 401(k) does two things, and only one of them is a market question. The investments carry the risk and the return everyone argues about. The employer match does not: it is a fixed multiple of what you put in, paid the moment you put it in, and it is the closest thing to a certain return that exists in a retirement account. A plan matching 50 cents on the dollar hands you an immediate 50% on every dollar up to its cap, before the market has done anything at all. That is why this page leads with the match rather than with a balance at 65. The balance depends on decades of returns nobody can promise; the match depends on one number in your payroll portal that you can change this afternoon.
Reading a match formula
Plan documents state the match as two numbers, and both matter. "50% up to 6% of pay" means the employer adds 50 cents for every dollar you contribute, and stops once your own contributions reach 6% of salary. "100% up to 4%" is a dollar-for-dollar match with a lower ceiling — more generous per dollar, less generous in total. On an $85,000 salary the first is worth $2,550 at full capture and the second $3,400. Contribute below the cap and you capture proportionally less; contribute above it and you shelter more income but earn no additional match, which is why the capture rate and the contribution rate are reported separately here. Some plans also stretch the formula deliberately — 25% up to 12% — to nudge people into contributing more for the same employer cost.
What a deferral actually costs you
The gap between what goes into the plan and what leaves your paycheck is the reason contribution rates are easier to raise than people expect. A pre-tax deferral reduces the wages your income tax is figured on, so at a 22% marginal rate a $130.77 deferral costs about $102 of take-home pay. Moving from 4% to 6% of an $85,000 salary — the change that captures the last $850 of match in the example on this page — is $1,700 more into the account and about $51 more per paycheck out of your pocket. A Roth deferral inside the plan works differently: it is taken from after-tax pay, so it costs the full amount now and comes out tax-free later. The Roth vs Traditional Calculator prices that trade properly.
The limits, and the one this page does not use
Two ceilings apply and they are often confused. The elective deferral limit — $24,500 for 2026, plus an $8,000 catch-up from age 50, or $11,250 for those aged 60 to 63 — applies to what you defer from your own pay. Employer money sits outside it, under a much higher combined limit on everything credited to the account in a year. Both are indexed and move most Januaries, which is why the limit here is an editable field rather than a constant. The limit check on this page is a year-one test: it tells you whether your current rate would breach this year's cap. It is deliberately kept out of the projection, because freezing a nominal cap across three decades of salary growth would understate a high earner's balance badly, and a calculator that projects an indexed limit is forecasting rather than calculating.
Frequently asked questions
Why does this page lead with the match instead of my balance at retirement?
Because the balance is a projection and the match is a decision you can act on this month. The Retirement Calculator already breaks a projected balance into contributions, employer money and growth. What no page had was the match formula itself — the one number where under-contributing costs you money that was already on the table.
Does contributing more than the match cap earn more match?
No. Once your contributions reach the share of pay the match stops at, the employer's part is maxed out. Contributing beyond that still shelters more income and still compounds, but it adds nothing to the match — which is why the page reports the capture rate separately from the amount.
Does the employer match count against the $24,500 deferral limit?
No. The elective deferral limit applies to what you defer from your own pay. Employer money sits outside it, under a much higher combined limit on everything that goes into the account in a year. The limit check on this page is a year-one test of your own contributions.
Why is the per-paycheck cost lower than my contribution?
A pre-tax deferral reduces the pay your income tax is figured on, so a dollar into the plan costs you less than a dollar of take-home. At a 22% marginal rate a $130.77 deferral costs about $102 of net pay. A Roth deferral inside the plan does not work this way — it costs the full amount now and comes out tax-free later.
What if my match vests over several years?
Vesting decides whether the match is yours if you leave, not whether it is paid. This page values the match as it is credited. If you are on a cliff schedule and plan to leave before it vests, treat the unvested part as money you may not keep.