How the 401(k) Calculator Works
Our calculator uses monthly compounding to project your 401(k) balance from today to your chosen retirement age. Each month, it applies your annual return rate to the current balance, then adds that month's share of your annual contributions and employer match. Salary growth compounds your contributions year-over-year, and the final balance is inflation-adjusted to show its value in today's dollars.
Growth Planner Tab
Enter your age, salary, contribution rate, employer match structure, and expected return. The calculator outputs your projected retirement balance, estimated monthly income using the 4% rule, and a stacked area chart breaking down contributions, employer match, and investment growth over time.
Scenario Compare Tab
Instantly compare four contribution rates (3%, 6%, 10%, 15%) against your current inputs. See how each scenario affects your final balance and how much extra wealth you accumulate by contributing more — keeping all other assumptions constant.
Year-by-Year Tab
View a detailed annual projection table showing your contribution, employer match, and investment gain at five-year milestones and at retirement. The retirement year row is highlighted for quick reference.
Inflation Adjustment
A large nominal balance in 30 years may sound impressive, but purchasing power matters. Enter an inflation rate (default 2.5%) and the calculator shows what your projected balance is worth in today's dollars.
2024 401(k) IRS Contribution Limits
Employee contribution limit
$23,000
Under age 50
Catch-up contribution limit
$30,500
Age 50 and older
Total combined limit
$69,000
Employee + employer contributions
These limits apply to traditional 401(k), safe harbor 401(k), and most 403(b) plans. SIMPLE IRA plans have lower limits. Limits are indexed to inflation and typically increase each year. Always verify current limits with the IRS website or a financial advisor.
Understanding Employer Match
Employer match is the single most valuable feature of a 401(k). Failing to contribute enough to capture the full match is equivalent to declining part of your compensation. Here are the most common match structures:
Dollar-for-Dollar Match
100% match on first 3% of salary
Employer matches every dollar you contribute up to 3% of your salary. On an $80,000 salary: contribute $2,400, receive $2,400 free.
Partial Match
50% match on first 6% of salary
Employer contributes 50 cents for every dollar you contribute, up to 6% of salary. On an $80,000 salary: contribute $4,800, receive $2,400 free.
Tiered Match
100% on first 3%, 50% on next 2%
A blended structure. The first 3% receives a full match; the next 2% receives a partial match. Common in larger corporate plans.
401(k) Calculation Examples
Example 1: The early starter
A 25-year-old earning $65,000 contributes 6% ($3,900/yr) with a 100% match on 3% ($1,950/yr). At 7% annual return over 40 years, the projected balance at age 65 exceeds $1.2 million — with less than $160,000 coming from personal contributions.
Example 2: The mid-career booster
A 40-year-old with a $50,000 existing balance earns $95,000 and increases contributions from 6% to 10%. The additional 4% contribution ($3,800/yr) over 25 years adds roughly $250,000 to the final balance — a meaningful difference for a relatively modest lifestyle adjustment.
Example 3: The catch-up contributor
A 52-year-old earning $120,000 uses the catch-up provision to contribute $30,500/yr with a $4,500 employer match. Over 13 years to age 65 at 7% return, the account can grow by over $700,000 — demonstrating how late starters can still build substantial savings.
Frequently Asked Questions
How much should I contribute to my 401(k)?+
At a minimum, contribute enough to capture your full employer match — that is free money with an instant 50–100% return. Beyond that, most financial planners recommend saving 10–15% of your gross salary in total retirement accounts. The 2024 IRS employee contribution limit is $23,000 ($30,500 if you are 50 or older).
What is a realistic 401(k) annual return to assume?+
A commonly used assumption is 7% per year, which reflects a diversified stock-heavy portfolio after adjusting for inflation. The S&P 500 has historically averaged roughly 10% annually before inflation. Conservative investors often model 5–6%. Use the calculator to test different scenarios.
How does employer match work in a 401(k)?+
Most employers match a percentage of your contributions up to a cap. A common structure is a 100% match on the first 3% of salary you contribute, meaning if you earn $80,000 and contribute 3%, your employer adds $2,400 per year at no extra cost to you.
Does employer match count toward the IRS contribution limit?+
No. The $23,000 employee limit (2024) applies only to your own deferrals. Employer contributions are tracked separately. The combined employee-plus-employer limit is $69,000 for 2024.
What is the 4% rule for retirement withdrawals?+
The 4% rule is a widely cited guideline suggesting you can withdraw 4% of your portfolio in year one of retirement, then adjust for inflation each year, and have a high probability of your savings lasting 30 or more years. A $1,000,000 portfolio would produce roughly $40,000 per year, or about $3,333 per month.
How is 401(k) growth calculated?+
Your 401(k) grows through three sources: your contributions, your employer's matching contributions, and compound investment returns on the total balance. Our calculator uses monthly compounding: each month, your balance earns its share of the annual return, and new contributions are added on top.
What happens to my 401(k) if I change jobs?+
You have four options: leave the money in your former employer's plan, roll it into your new employer's 401(k), roll it into an IRA, or cash it out. Cashing out before age 59½ triggers ordinary income tax plus a 10% early withdrawal penalty, so it is generally the least favorable choice.
Can I withdraw from my 401(k) without penalty?+
Penalty-free withdrawals are available at age 59½. Before that, most withdrawals trigger a 10% early withdrawal penalty plus income tax, unless you qualify for an exception such as a hardship withdrawal, substantially equal periodic payments (SEPP), or separation from service at age 55 or older.
What is the difference between a traditional 401(k) and a Roth 401(k)?+
Traditional 401(k) contributions are made pre-tax, reducing your taxable income today but requiring you to pay taxes on withdrawals in retirement. Roth 401(k) contributions are made after-tax, so withdrawals in retirement are tax-free. Which is better depends on whether you expect to be in a higher or lower tax bracket in retirement.
How does salary growth affect my 401(k) projection?+
Because contributions are a percentage of salary, even modest annual raises compound significantly over a 30-year career. A 2% annual salary growth assumption means your contributions increase each year, accelerating balance growth beyond what a fixed-salary model would project.
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Estimates & Assumptions
- Returns are compounded monthly using a fixed annual rate. Actual market returns vary year-to-year and are not guaranteed.
- Contributions are capped at the 2024 IRS employee limit of $23,000 per year (or $30,500 for users aged 50+; this calculator applies the standard limit — adjust manually for catch-up eligibility).
- Employer match is calculated based on the match rate and cap you enter. Vesting schedules are not modelled; amounts shown assume immediate full vesting.
- Salary growth is applied annually at the rate you specify, increasing contributions in proportion. Taxes on contributions and withdrawals are not modelled.
- Inflation adjustment divides the final nominal balance by the compounded inflation factor over the projection period.
This calculator is for educational and estimation purposes only. Results are projections, not guarantees. Investment performance, tax law, contribution limits, and plan rules change over time. Consult a certified financial planner or tax advisor before making retirement planning decisions.