A 401k calculator is the fastest way to see whether your current contribution rate is actually on track to fund retirement, or whether you're quietly leaving employer money on the table. Plug in your age, salary, and contribution percentage, and the numbers do the arguing for you β no guesswork, no spreadsheet.
We built this tool at Arb Digital because so many of the calculators floating around online either ignore the employer match entirely or bury it in fine print. That's backwards. The match is usually the single highest-return piece of your entire retirement plan, and it deserves top billing.
What This 401k Calculator Does
Enter your current age, target retirement age, existing balance, salary, contribution percentage, and your employer's match formula. The calculator compounds your contributions, your employer's match, and investment growth year by year, while also increasing your salary by an assumed annual raise. The result is a realistic projection of what your account could look like the day you retire β broken down into how much came from you, how much came from your employer, and how much came purely from growth.
Unlike a static "set it and forget it" spreadsheet formula, this projection recalculates your dollar contribution every single year as your salary rises, and it recalculates your employer match right alongside it. That matters more than it sounds. A flat 8% contribution on a $80,000 salary is $6,400 a year; the same 8% on a $120,000 salary two decades later is $9,600. Because your match is also tied to your salary and contribution rate, it climbs in lockstep β which is exactly why long careers with steady raises tend to produce dramatically larger 401(k) balances than a simple back-of-envelope estimate would suggest.
A Real-World Example Walkthrough
Take a 35-year-old earning $80,000 with $50,000 already saved, contributing 8% of salary, with an employer matching 50% up to 6% of pay, a 7% expected return, and 2% annual raises through age 65. In year one, that's a $6,400 employee contribution and a $2,400 employer match (50% of the 6% of salary the employer matches, or $4,800, times 50%). Both amounts get added to the $50,000 balance and grow at 7% for the year. Salary then rises to $81,600, and the cycle repeats for the next 29 years. Small annual gains like this compound into a surprisingly large gap by retirement β which is exactly the kind of scenario this calculator is built to surface instantly, without you tracking three decades of spreadsheet rows by hand.
How to Use the 401k Calculator
- Enter your current age and target retirement age. Most people use 65, but you can model an earlier or later exit.
- Enter your current 401(k) balance. Check your last statement or plan portal for the exact figure.
- Enter your annual salary. Use your gross salary before taxes.
- Enter your contribution percentage. This is the share of each paycheck you defer into the plan.
- Enter your employer's match percentage and cap. For example, "50% up to 6%" means your employer adds 50 cents for every dollar you contribute, capped at 6% of your salary.
- Enter your expected return and salary growth rates, then click Calculate to see your projected balance and monthly retirement income.
The Formula Behind the Numbers
Each year, the calculator adds your contribution and the matching employer contribution to your balance, then applies your expected annual return. Your salary is then increased by your assumed growth rate before the next year runs. This is a standard compound-growth model, similar to the guidance published by the IRS on 401(k) contribution limits. For 2025, the employee deferral limit is $23,500, with an additional $7,500 catch-up contribution allowed if you're 50 or older β figures you should keep in mind if your contribution percentage would push you past the cap.
Why the Employer Match Is a 50β100% Instant Return
No stock, bond, or index fund can promise you a guaranteed 50% or 100% return the moment you invest. Yet that's exactly what an employer match delivers. If your company matches 50% of your contributions up to 6% of your salary, contributing that full 6% instantly turns into a 50% return before your money has even touched the market. Skip it, and you're not just missing an investment opportunity β you're declining part of your compensation package, no different than leaving a bonus check uncashed in a drawer.
This is why financial planners almost universally recommend contributing at least enough to capture the full match before doing anything else with extra cash, including paying down low-interest debt or building a taxable brokerage account. It's the closest thing to a free lunch in personal finance.
Contribution Percentage Beats Fund-Picking
People spend hours agonizing over which target-date fund or index fund to choose inside their 401(k), while ignoring the much bigger lever sitting right in front of them: the contribution percentage. Bumping your deferral rate from 6% to 10% of salary will move the needle on your retirement balance far more than swapping between two reasonably diversified fund options ever will. Use this calculator to test a few contribution percentages side by side β the gap in projected outcomes tends to be eye-opening, especially over a 20- or 30-year career.
Watch the 2025 Contribution Limit
The IRS adjusts 401(k) limits most years for inflation. For 2025, employees under 50 can defer up to $23,500, and those 50 and older can add a $7,500 catch-up contribution for a combined $31,000. If your salary and contribution percentage would put you above that ceiling, your actual paycheck deferral will be capped once you hit the limit β something payroll systems generally handle automatically, but worth knowing so this projection lines up with your real paystub.
There's also a separate, higher combined limit that covers your contributions plus your employer's match plus any additional profit-sharing contributions together β a figure the IRS also updates annually. Most employees never come close to that combined ceiling, since it takes a fairly generous employer contribution formula or a high salary to approach it, but highly compensated employees at smaller companies occasionally do. If you're unsure where you stand, your plan administrator's year-end statement will show exactly how your contributions and any employer amounts add up against both limits.
Traditional vs. Roth 401(k) Contributions
Many employers now offer a Roth option inside the 401(k) plan alongside the traditional pre-tax option. This calculator models the traditional pre-tax version, where your contribution reduces your taxable income today and withdrawals are taxed later. A Roth 401(k) works the opposite way β contributions are made after tax, but qualified withdrawals in retirement are entirely tax-free, similar to a Roth IRA, except a Roth 401(k) has no income limit and allows the same higher contribution cap as the traditional version. If your plan offers both, splitting contributions between the two β or leaning into whichever matches your current versus expected future tax bracket β is worth a closer look alongside this projection.
Compare this projection against a Roth or Traditional IRA, or check your required minimum distributions later in life.
Try the Roth IRA Calculator All Free ToolsVesting Schedules Matter Too
Not every dollar your employer contributes is guaranteed to be yours immediately. Many plans use a vesting schedule, meaning you only fully own the employer match after a certain number of years of service β sometimes gradually (20% per year over five years, for example) and sometimes all at once at a specific milestone ("cliff" vesting). Your own contributions are always 100% vested immediately, but the match may not be. If you're considering leaving a job, it's worth checking your plan's vesting schedule before you go, since unvested employer contributions are typically forfeited if you leave too early.
Common Mistakes to Avoid
- Contributing less than the match threshold. Always contribute enough to capture 100% of the available employer match first.
- Ignoring salary growth. As your pay rises, your contribution in dollar terms rises too β even at a flat percentage, so don't underestimate future contributions.
- Assuming an unrealistic return. A 7% average annual return is a common long-term planning assumption, but real markets are volatile year to year.
- Forgetting fees. High plan administration or fund expense ratios can quietly erode years of growth β check your plan's fee disclosure.
- Never increasing your contribution rate. Many plans offer auto-escalation; a 1% annual bump is barely noticeable in your paycheck but compounds significantly over decades.
Related Free Tools From Arb Digital
Curious how a 401(k) stacks up against other retirement accounts? Try the Roth IRA Calculator and the Traditional IRA Calculator to compare tax treatment, or use our original Retirement Calculator for a broader nest-egg projection. If you're already 73 or approaching it, the RMD Calculator shows what the IRS will require you to withdraw. You can also explore every calculator we offer on the free online tools hub.
Frequently Asked Questions
At minimum, contribute enough to capture your full employer match β that's an immediate, guaranteed return. Beyond that, many planners suggest working toward 10β15% of salary including the match, adjusted for your age and other savings goals.
For 2025, the IRS employee deferral limit is $23,500, with an additional $7,500 catch-up contribution allowed for participants age 50 and older, for a combined $31,000.
No. Employer matching contributions do not count toward your personal $23,500 employee deferral limit, though there is a separate, higher combined limit for total contributions from both you and your employer.
7% is a commonly used long-term planning assumption for a diversified stock-and-bond portfolio, but actual results vary year to year. Try running the calculator at a few different rates to see a range of outcomes.
The "4% rule" is a widely cited historical guideline for sustainable withdrawals, but it isn't guaranteed for every market environment or retirement length. Treat the monthly income estimate here as a starting reference point, not a fixed promise.
You can typically leave it with your former employer's plan, roll it into your new employer's 401(k), or roll it into an IRA. Cashing it out early usually triggers taxes and a 10% penalty if you're under 59Β½.
This tool provides general estimates for educational purposes only and is not financial, tax, legal, or medical advice. Figures are illustrative; consult a licensed professional for decisions.
