How 401(k) Retirement Calculator Works
Our free 401(k) calculator projects your retirement balance with real-world complexity — not just simple compound growth, but employer match modeling, vesting schedules, Traditional vs Roth comparison, catch-up contributions, and multiple growth scenarios.
You enter your current age, retirement age, salary, contribution percentage, employer match formula, and current 401(k) balance. The calculator then projects year-by-year growth showing your contributions, employer match (subject to vesting), and investment returns compounding over time.
The employer match modeling handles real-world formulas: "50% match on first 6%" or "100% match on first 3%, 50% on next 2%." Combined with your vesting schedule (immediate, cliff, or graded), you see exactly how much of the match you actually keep if you leave before full vesting.
The Traditional vs Roth comparison is the tool's most valuable feature. It models your tax savings today (Traditional) versus tax-free growth and withdrawals (Roth), then projects which produces more after-tax retirement income based on your current and expected future tax brackets. For most young workers in lower brackets, Roth wins. For high earners near peak income, Traditional often wins.
Three growth scenarios (conservative 5%, moderate 7%, aggressive 9%) show the range of outcomes so you can plan for both good and bad market environments.
Pair with the Compound Interest Calculator for general investment projections, or the Retirement Withdrawal Strategy Planner to model how you'll spend your 401(k) in retirement.
Key Terms Explained
- 401(k) Contribution Limit
- The IRS maximum you can contribute per year — $23,500 in 2026 for workers under 50, $31,000 for workers 50+ (includes $7,500 catch-up contribution).
- Employer Match
- Free money from your employer that matches your contributions up to a formula — commonly 50% of the first 6% of salary, or 100% of the first 3%.
- Vesting Schedule
- The timeline for owning your employer's match contributions. Immediate vesting means it's yours right away. Cliff vesting gives 100% after a set period. Graded vesting increases ownership yearly.
- Traditional 401(k)
- Pre-tax contributions that reduce your taxable income now. You pay income tax on withdrawals in retirement. Best when your current tax rate is higher than your expected retirement rate.
- Roth 401(k)
- After-tax contributions with no immediate tax benefit. Withdrawals in retirement (including growth) are 100% tax-free. Best when your current tax rate is lower than your expected retirement rate.
- Catch-Up Contribution
- An additional $7,500/year that workers age 50+ can contribute above the standard limit, designed to help people closer to retirement accelerate their savings.
Who Needs This Tool
Just started a job with a 401(k) and wants to know: how much should I contribute, should I choose Traditional or Roth, and how much will I have at retirement?
Earning $120,000 at age 40 and wants to project whether maxing out contributions will produce enough for early retirement at 55.
Has 2 years vested on a 6-year graded vesting schedule and wants to understand how much employer match they'd forfeit by leaving now.
Hasn't saved enough for retirement and wants to model the impact of maxing out contributions with catch-up for the next 15 years.
Methodology & Formulas
Year-by-year projection: Balance(n+1) = (Balance(n) + Employee Contribution + Vested Employer Match) × (1 + Return Rate). Employee contribution = min(Salary × Contribution%, Annual Limit). Employer match = min(Salary × Match Formula, Match Cap). Vesting: Cliff = 0% until cliff year then 100%; Graded = proportional increase per year. Traditional tax savings = Contribution × Marginal Rate. Roth future value advantage = no taxes on withdrawals in retirement.
Pro Tips
- At minimum, contribute enough to get the full employer match — anything less is literally leaving free money on the table (an immediate 50-100% return on investment).
- If you expect your income to grow significantly, Roth 401(k) now locks in today's lower tax rate. You'll thank yourself when withdrawals are tax-free in retirement.
- The difference between contributing 6% and 15% of a $75K salary is massive over 30 years: ~$600K vs $1.5M at 7% returns. Start high early.
- Don't count unvested employer match as 'your money' when evaluating job changes — only the vested portion is guaranteed if you leave.
- Annual raises are the easiest time to increase contributions — commit half of every raise to 401(k) and you won't feel the lifestyle impact.