401(k) Calculator
Enter your age, salary, contribution rate, employer match, and expected return. The calculator projects your 401(k) balance at retirement.
Total at retirement:
Your total contributions:
Total employer match:
Investment growth:
How the 401(k) Calculator Works
The 401(k) calculator projects how much your employer-sponsored retirement account will grow by the time you retire. It factors in your current balance, annual contributions, employer matching contributions, and compound investment returns over the years remaining until retirement. Understanding how these variables interact helps you make informed decisions about contribution rates and investment strategies to build long-term wealth.
401(k) Growth Formula
Each year your balance grows through three mechanisms — your contributions, employer matching, and investment returns. The projection uses the following year-over-year calculation:
Balance(year) = Balance(year-1) × (1 + Annual Return) + Annual Contribution + Employer Match
The annual contribution equals your salary multiplied by your contribution rate. The employer match is calculated similarly using the match percentage.
Worked Example
Consider a 30-year-old earning $75,000/year with a current 401(k) balance of $25,000, contributing 10%, receiving a 4% employer match, and expecting 7% annual returns until age 65:
- Years to retirement: 65 − 30 = 35 years
- Annual contribution: $75,000 × 10% = $7,500
- Annual employer match: $75,000 × 4% = $3,000
- Total added per year: $7,500 + $3,000 = $10,500
After 35 years of compound growth at 7%, the projected balance reaches approximately $1,648,000 — even though total out-of-pocket contributions were only $262,500. The power of compounding and employer matching accounts for the majority of the final balance.
Understanding 401(k) Plans
A 401(k) is a tax-advantaged retirement savings plan offered by employers in the United States. Named after Section 401(k) of the Internal Revenue Code, these plans allow employees to defer a portion of their salary into an investment account that grows tax-deferred until withdrawal in retirement.
2024 Contribution Limits
The IRS sets annual limits on how much you can contribute to your 401(k):
| Category | 2024 Limit |
|---|---|
| Employee contribution (under 50) | $23,000 |
| Catch-up contribution (50+) | $7,500 additional |
| Total employee + employer | $69,000 |
| Total with catch-up (50+) | $76,500 |
These limits increase periodically to adjust for inflation. Always check the current IRS guidelines for the most up-to-date figures.
Employer Matching
Many employers match a portion of employee contributions, effectively giving you free money toward retirement. Common match formulas include:
- Dollar-for-dollar up to a percentage — e.g., 100% match on the first 4% of salary
- Partial match — e.g., 50% match on the first 6% of salary (equivalent to 3%)
- Tiered match — e.g., 100% on the first 3%, then 50% on the next 2%
Financial advisors universally recommend contributing at least enough to capture the full employer match. Leaving match money on the table is essentially declining part of your compensation package.
Traditional vs. Roth 401(k)
Many employers now offer both Traditional and Roth 401(k) options:
Traditional 401(k): Contributions are made with pre-tax dollars, reducing your current taxable income. Withdrawals in retirement are taxed as ordinary income. This benefits people who expect to be in a lower tax bracket during retirement.
Roth 401(k): Contributions are made with after-tax dollars — no immediate tax break. However, qualified withdrawals in retirement are completely tax-free, including all investment gains. This benefits younger workers who expect higher income and tax rates in the future.
Both types share the same contribution limits, and many savers split contributions between the two to diversify their tax exposure in retirement.
The Power of Starting Early
Compound growth rewards time more than contribution size. Consider this comparison:
| Scenario | Start Age | Monthly Savings | Balance at 65 (7% return) |
|---|---|---|---|
| Early start | 25 | $500 | $1,198,000 |
| Mid-career start | 35 | $500 | $567,000 |
| Late start | 45 | $500 | $246,000 |
| Late start (double) | 45 | $1,000 | $492,000 |
Starting at 25 instead of 35 more than doubles the final balance — and the early starter contributes only $60,000 more in total. Even doubling the monthly contribution at 45 cannot fully make up for the lost years of compounding.
Vesting Schedules
Employer matching contributions may be subject to a vesting schedule, meaning you only own the matched funds after working for the company for a certain period. Common schedules include:
- Immediate vesting — you own matched funds right away
- Cliff vesting — 0% vested until a set date (usually 3 years), then 100%
- Graded vesting — vesting increases gradually (e.g., 20% per year over 5 years)
Your own contributions are always 100% vested immediately.
Frequently Asked Questions
How much should I contribute to my 401(k)?
Financial advisors generally recommend saving 10–15% of gross income for retirement. At minimum, contribute enough to get the full employer match — otherwise you are giving up free money.
What happens to my 401(k) if I change jobs?
You can roll your 401(k) into your new employer's plan or into an IRA. Leaving it in the old plan is also an option, but rolling over gives you more investment choices and consolidates your accounts.
Can I withdraw from my 401(k) before retirement?
Early withdrawals before age 59½ typically incur a 10% penalty plus income taxes. Exceptions include hardship withdrawals, the Rule of 55, and certain disability or medical situations.
What is the difference between a 401(k) and an IRA?
A 401(k) is employer-sponsored with higher contribution limits ($23,000 in 2024). An IRA is individually opened with a $7,000 annual limit ($8,000 if 50+). Both offer tax advantages but differ in contribution limits, investment options, and access.
Does the calculator account for salary increases?
This calculator uses a fixed salary for simplicity. In reality, salary growth would increase contributions over time, potentially resulting in a higher balance than projected.
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Sources
- IRS: 401(k) Plan Overview
- IRS: 2024 Contribution Limits
- U.S. Department of Labor: What You Should Know About Your Retirement Plan
- Investopedia: 401(k) Plans