401(k) Calculator — Retirement Growth
Calculate how your 401(k) will grow with employer matching, compound returns, and catch-up contributions.
Formula
FV = PV(1+r)^n + PMT(emp+match) × [((1+r)^n - 1) / r]
Future Value equals current balance grown by compound returns, plus the accumulated value of employee contributions and employer matching. Account for contribution limits, vesting, and catch-up contributions for those 50+.
Worked Examples
Example 1: Maximizing Employer Match Value
Problem:Age 30, earning $80,000/year with 100% match up to 5% of salary. Contributing 5% to get full match. What's this worth at age 65 at 7% returns?
Solution:Annual employee contribution: $80,000 × 5% = $4,000 Annual employer match: $80,000 × 5% × 100% = $4,000 Total annual: $8,000 Future value of $8,000/year for 35 years at 7%: FV = $8,000 × [((1.07)^35 - 1) / 0.07] FV = $8,000 × 138.24 FV = $1,105,900 Employer match contribution over 35 years: $140,000 Value of employer match at retirement: $552,950 (half of total)
Result:Employer match worth $552,950 at retirement from $140,000 in match contributions
Example 2: Impact of Starting Early
Problem:Compare starting 401(k) at age 25 vs 35, both contributing $6,000/year until 65 with 7% returns.
Solution:Starting at 25 (40 years of contributions): FV = $6,000 × [((1.07)^40 - 1) / 0.07] FV = $6,000 × 199.64 FV = $1,197,810 Total contributed: $240,000 Starting at 35 (30 years of contributions): FV = $6,000 × [((1.07)^30 - 1) / 0.07] FV = $6,000 × 94.46 FV = $566,765 Total contributed: $180,000 Difference: $1,197,810 - $566,765 = $631,045 more
Result:Starting 10 years earlier yields $631,045 more despite only $60,000 more contributed
Example 3: Catch-Up Contribution Impact
Problem:Age 50, current balance $400,000. Compare contributing $23,000/year vs $30,500/year (with catch-up) for 15 years at 7%.
Solution:Without catch-up ($23,000/year): Current balance growth: $400,000 × (1.07)^15 = $1,103,613 Contribution growth: $23,000 × [(1.07^15 - 1) / 0.07] = $577,968 Total: $1,681,581 With catch-up ($30,500/year): Current balance growth: $1,103,613 (same) Contribution growth: $30,500 × [(1.07^15 - 1) / 0.07] = $766,435 Total: $1,870,048 Difference: $188,467 more from catch-up
Result:Catch-up contributions add $188,467 to retirement savings over 15 years
Frequently Asked Questions
What is a 401(k) and how does it work?
A 401(k) is an employer-sponsored retirement savings plan that offers tax advantages. You contribute a percentage of your salary before taxes (traditional 401(k)) or after taxes (Roth 401(k)). The money grows tax-deferred until withdrawal in retirement. Many employers match a portion of your contributions - essentially free money. In 2024, you can contribute up to $23,000, plus an additional $7,500 if you're 50 or older. Withdrawals before age 59½ typically incur a 10% penalty plus income taxes.
How does employer matching work?
Employer matching is when your company contributes to your 401(k) based on what you contribute. A common match is 50% of your contribution up to 6% of salary. Example: If you earn $80,000 and contribute 6% ($4,800), your employer adds 50% of that ($2,400). That's an instant 50% return! Matches vary: some employers match 100%, some have dollar limits, some use tiered structures. Always contribute at least enough to get the full match - anything less leaves free money on the table.
What's the difference between traditional and Roth 401(k)?
Traditional 401(k): Contributions are pre-tax (reduces current taxable income), grows tax-deferred, withdrawals taxed as ordinary income. Best if you expect lower tax rates in retirement. Roth 401(k): Contributions are after-tax (no immediate tax benefit), grows tax-free, qualified withdrawals are completely tax-free. Best if you expect higher tax rates in retirement or want tax diversification. Many advisors recommend splitting contributions between both for flexibility. Both have the same contribution limits.
How much should I contribute to my 401(k)?
At minimum, contribute enough to get your full employer match - otherwise you're leaving free money on the table. General recommendations: 15% of salary including employer match is a good target. Start at 10% if you have debt, increase with raises. If starting late (over 40), aim for 20%+. Max out if you can ($23,000 in 2024, $30,500 if 50+). The power of compound growth means even small increases early on lead to significantly larger retirement savings.
What are 401(k) catch-up contributions?
Catch-up contributions allow employees aged 50 and older to save extra beyond the standard limit. For 2024: Standard limit is $23,000. Catch-up contribution is an additional $7,500. Total for 50+ is $30,500. This recognizes that older workers often have more disposable income (mortgage paid off, kids independent) and less time to save. If you're 50+ and behind on savings, maximizing catch-up contributions can significantly boost your retirement nest egg. The extra $7,500/year at 7% for 15 years adds about $200,000.
What happens to my 401(k) if I leave my job?
You have several options: 1) Leave it with former employer (if allowed, typically for balances over $5,000). 2) Roll over to new employer's 401(k) - keeps everything in one place. 3) Roll over to an IRA - more investment options, possibly lower fees. 4) Cash out - AVOID if possible; you'll pay income taxes plus a 10% penalty if under 59½, losing significant value. Rollovers should be 'direct' (trustee-to-trustee) to avoid withholding. Take your time deciding - you don't have to act immediately.
What are the tax implications of 401(k) withdrawals?
Traditional 401(k) withdrawals are taxed as ordinary income in the year of withdrawal. Early withdrawals (before 59½) also incur a 10% penalty (with some exceptions). Required Minimum Distributions (RMDs) must begin at age 73, forcing taxable withdrawals whether you need the money or not. Roth 401(k) qualified withdrawals (after 59½ and 5-year holding) are completely tax-free. Strategy tip: Roth conversions during low-income years (early retirement, between jobs) can reduce future tax burden.
Should I take a 401(k) loan?
401(k) loans let you borrow up to 50% of your balance or $50,000, whichever is less. You repay with interest to yourself. Pros: No credit check, low interest (usually prime + 1%), repayments go back to your account. Cons: Double taxation (repay with after-tax dollars, then taxed again at withdrawal), miss out on market gains, must repay within 5 years (usually immediately if you leave your job). Generally avoid unless it's for a true emergency and you've exhausted other options. Hardship withdrawals are also possible but more restrictive.
What fees should I watch for in my 401(k)?
401(k) fees can significantly impact returns over time. Types of fees: 1) Expense ratios on funds (0.03% for index funds to 2% for actively managed). 2) Administrative fees charged by the plan. 3) Individual service fees (for loans, distributions). A 1% difference in fees can reduce your balance by 25%+ over 30 years. Look for low-cost index funds (S&P 500, total market). Review your plan's fee disclosure document annually. If your plan has only high-fee options, contribute enough for the match, then use an IRA for additional savings with lower-cost options.
What is the difference between a traditional and Roth retirement account?
Traditional 401(k)/IRA contributions reduce taxable income today but withdrawals in retirement are taxed as ordinary income. Roth accounts use after-tax contributions with no upfront deduction, but qualified withdrawals (age 59½+, 5-year holding) are completely tax-free including all growth. Choose Roth if you expect higher taxes in retirement; choose traditional if you expect lower rates. Roth IRAs have no required minimum distributions, unlike traditional accounts. Holding both provides tax flexibility at withdrawal.
Background & Theory
The 401(k) is the cornerstone of retirement savings for millions of Americans. Understanding how these plans work - from contribution limits to employer matches to investment options - is essential for building retirement security.
Key 401(k) Concepts:
Pre-Tax vs. Roth Contributions:
- Traditional (pre-tax): Reduces current taxable income, taxed at withdrawal
- Roth: No immediate tax benefit, tax-free withdrawals in retirement
- Both have same contribution limits
- Choice depends on current vs. expected future tax rates
2024 Contribution Limits:
- Under 50: $23,000 employee contribution
- 50 and older: $30,500 (includes $7,500 catch-up)
- Total including employer contributions: $69,000 (or $76,500 with catch-up)
Employer Matching:
Common match structures:
- Dollar-for-dollar up to 3% (contribute 3%, get 3%)
- 50 cents per dollar up to 6% (contribute 6%, get 3%)
- Tiered: 100% on first 3%, 50% on next 2%
- Fixed dollar amount regardless of contribution
Match value calculation:
Match Value = Contribution × Match Rate × Years × Growth Factor
Vesting Schedules:
Employer contributions often have vesting requirements:
- Cliff vesting: 0% until X years (usually 3), then 100%
- Graded vesting: 20% per year over 5-6 years
- Your contributions are always 100% vested immediately
Investment Options:
Typical 401(k) menus include:
- Target-date funds (automatic age-based allocation)
- Index funds (low-cost market tracking)
- Actively managed funds (higher cost, variable performance)
- Stable value/money market (capital preservation)
- Company stock (often with discount, but risky to over-concentrate)
Asset Allocation Guidelines:
Age-based stock allocation rules of thumb:
- 110 minus age = stock percentage
- More aggressive: 120 minus age
- More conservative: 100 minus age
Example for age 30: 110 - 30 = 80% stocks, 20% bonds
Tax Implications:
Traditional 401(k):
- Contributions reduce current taxable income
- All withdrawals taxed as ordinary income
- Required Minimum Distributions (RMDs) begin at 73
- Early withdrawal penalty: 10% plus income taxes
Roth 401(k):
- Contributions made with after-tax dollars
- Qualified withdrawals completely tax-free
- No lifetime RMDs beginning in 2024 under SECURE 2.0, matching Roth IRA treatment
- No early withdrawal penalty on contributions
Rollovers and Job Changes:
When leaving an employer:
- Leave in old plan (if balance exceeds the plan's force-out limit, up to $7,000 since 2024)
- Roll to new employer's 401(k)
- Roll to Traditional IRA (more investment options)
- Roll to Roth IRA (pay taxes now, tax-free later)
- Cash out (avoid - taxes plus 10% penalty)
Direct rollovers (trustee-to-trustee) avoid mandatory withholding.
401(k) Loans:
- Borrow up to 50% of balance or $50,000
- Must repay within 5 years (unless for home purchase)
- Interest paid to yourself
- Immediate repayment if you leave employer
- Miss out on market gains while borrowed
Common Mistakes:
- Not contributing enough to get full match
- Too conservative allocation when young
- Cashing out when changing jobs
- Not rebalancing portfolio
- Too much company stock
- Ignoring fees
- Not increasing contributions with raises