A 401(k) is the single most powerful tax-advantaged savings tool most working Americans have, yet the number people most often guess at — how much to actually contribute — is also the one that pays off the most to get right. This 401(k) contribution calculator turns your salary, your employer's match formula, the IRS annual limit, and your tax bracket into three concrete numbers: what you defer each year, what your employer adds on top, and what that combination grows into by the time you retire.
Adjust the sliders and the result updates instantly. You will see exactly how much each paycheck shrinks after the tax deduction, how much "free match" income you are leaving on the table, and the difference between contributing enough to get the full match and maxing out the entire annual limit.
How to Use
- Enter your Annual Salary — your gross pay before any 401(k) deferral. The match and your deferral percentage are both computed off this figure.
- Set Your Contribution as a percentage of salary. A common starting point is 10%, but the most important minimum is the rate needed to capture your full employer match.
- Confirm the Annual IRS Deferral Limit. For 2024 the employee elective-deferral cap is $23,000; if you are 50 or older, add the $7,500 catch-up. The calculator automatically stops your deferral at this limit.
- Enter your Employer Match rate. The classic formula is a 50% match on the portion of your own contribution up to a set share of salary.
- Set the Match Cap — the salary percentage up to which your employer matches. A 6% cap means that once you defer 6% of pay, the match stops growing.
- Add your Marginal Tax Bracket. Every pre-tax dollar you defer reduces your taxable income at this rate, which is how the annual tax-savings line is produced.
- Optionally set your Expected Annual Return, Years Until Retirement, and Paychecks Per Year to project the future balance and the per-paycheck cost.
The result card shows your annual deferral, the employer match, the combined annual contribution, your immediate tax savings, the amount withheld from each paycheck, your true after-tax paycheck reduction, and a projected balance at retirement.
How the Numbers Are Built
Your own deferral is simply salary times your contribution percentage, but it cannot legally exceed the IRS elective-deferral limit for the year. If your chosen percentage would push you past that cap, the engine takes the smaller of the two — that is why a high earner who defers 15% of a $200,000 salary still stops at $23,000.
The employer match is the part most people leave on the table. It is calculated as your match percentage applied to your own deferral, but only up to the match cap. With a 50% match on contributions up to 6% of salary, the employer adds 50 cents for every dollar you defer until you have deferred 6% of pay. Once you cross 6%, your own savings keep going but the match plateaus.
Because traditional 401(k) contributions are pre-tax, every deferred dollar lowers your taxable income. At a 22% marginal bracket, deferring $8,000 saves you $1,760 in federal tax this year — meaning the paycheck hit is smaller than the gross deferral suggests. The future balance uses the ordinary-annuity formula, growing your combined annual contribution at your assumed return until retirement.
Examples
Example 1 — The baseline ($80,000 salary, 10% deferral). On an $80,000 salary at a 10% deferral, you put in $8,000 a year. The match threshold is 6% of salary, or $4,800, and the 50% match adds $2,400. Combined, $10,400 goes into the plan each year. At a 22% bracket you save $1,760 in tax, the biweekly deferral is about $308 per paycheck, and after the tax shield your take-home pay actually falls by only about $240. At a 7% return over 30 years, that grows to roughly $982,392.
Example 2 — Leaving match on the table. If the same person contributes only 3% of salary ($2,400) instead of 10%, the match shrinks to just $1,200 — they forfeit $1,200 of free employer money every single year. That is an instant 50% return on the first few thousand dollars saved, which no low-risk investment can match. Contributing at least enough to get the full match is the highest-return financial decision most people will ever make.
Example 3 — High earner hitting the $23,000 cap. At a $1.5 million salary deferring 15%, your raw deferral would be $225,000, but the IRS cap holds it to $23,000. With a 50% match up to 6% of salary, the employer adds $11,500 (half of your capped deferral, since your deferral already exceeds the 6% threshold). The combined $34,500 a year, growing at 7% over 30 years, projects to about $3.26 million — and the $23,000 deferral cuts a 22% tax bill by $5,060 in the very first year.
FAQ
How much should I contribute to my 401(k)?
At minimum, contribute enough to receive your full employer match. With a 50%-up-to-6% formula, deferring 6% of salary captures the entire match — an immediate, guaranteed 50% return on that portion. Once you get the full match, work toward 10–15% of pay, and max out the $23,000 limit if your budget allows. Use the slider above to watch the match and tax-savings lines move.
What is the 401(k) contribution limit for 2024?
For 2024, employees can defer up to $23,000 of their own salary into a 401(k). If you are age 50 or older, you can add a $7,500 catch-up contribution, bringing the employee total to $30,500. These limits are adjusted most years for inflation, so confirm the current figure on the IRS website.
How does the employer match actually work?
A typical match is 50% of your own contribution, but only on the portion of your contribution that falls within a set percentage of your salary — often 6%. So if you defer 6% of pay, your employer adds 3% of pay; if you defer more than 6%, the employer still only adds that same 3%. The match is free money and vests on a schedule set by your plan.
Will contributing to my 401(k) shrink my paycheck too much?
Less than the gross amount suggests. Because traditional 401(k) contributions are pre-tax, you defer the money before income tax is calculated. At a 22% bracket, a $308 per-paycheck deferral reduces your take-home pay by only about $244. The calculator shows both the gross per-paycheck deferral and the net after-tax reduction so you can budget the real number.
Do 401(k) contributions save on taxes?
Yes. Traditional 401(k) deferrals lower your taxable dollar-for-dollar, so a $8,000 deferral at a 22% marginal bracket saves you $1,760 in federal income tax in that year. You pay ordinary income tax later when you withdraw in retirement, when many people are in a lower bracket. Roth 401(k) contributions do not give an upfront deduction but are tax-free in retirement.
What is the difference between Roth and pre-tax 401(k)?
Pre-tax (traditional) contributions lower your tax bill today and are taxed when withdrawn in retirement. Roth 401(k) contributions are made with after-tax dollars — no upfront deduction — but qualified withdrawals in retirement are completely tax-free. If you expect a higher tax rate in retirement, lean Roth; if you expect a lower rate, lean pre-tax. Many people split between the two.
Disclaimer
This 401(k) contribution calculator is provided for informational purposes only and does not constitute financial, tax, or investment advice. Estimates use the inputs you enter and standard IRS contribution limits and annuity-growth math; actual plan rules, vesting schedules, state taxes, investment returns, and limits vary by employer and year and may change. Projected balances are hypothetical and do not guarantee future results. Always consult a qualified financial or tax professional before changing your contribution elections.