401(k) Calculator

About the 401(k) Calculator

A 401(k) calculator helps you project the future balance of your employer-sponsored retirement account based on your current savings, contribution rate, employer match, and expected investment returns. The 401(k) is the cornerstone of retirement savings for most American workers — a tax-advantaged account that allows you to defer income taxes on contributions until retirement, invest in a range of funds, and receive free money through employer matching. Yet many employees contribute only enough to get the full match — a good start, but often not enough to retire comfortably. Our free 401(k) calculator models the full growth of your account from today to your target retirement age, factoring in both your annual contributions and your employer match. It shows the compounded impact of different contribution rates and helps you understand whether your current savings trajectory will meet your retirement income goals. The results often motivate higher contributions because the difference between saving 6% and 15% of salary, compounded over decades, is frequently in the hundreds of thousands of dollars.

How It Works

The 401(k) projection uses a year-by-year compound growth model: each year, your starting balance grows by the expected return rate, then your annual employee contributions and employer match are added. The formula is: Balance(year+1) = Balance(year) x (1 + r) + Employee Contribution + Employer Match. Employer match = min(your contribution, salary x match cap%) x match rate%. Example: Age 30, $75,000 salary, $25,000 current balance, 10% contribution ($7,500/year), 50% match up to 6% of salary (match = $2,250/year), 7% annual return, retiring at 65. Year 1: $25,000 x 1.07 + $7,500 + $2,250 = $36,500. After 35 years of compounding: projected balance approximately $1.7 million. Total employee contributions over 35 years: $262,500. Total employer contributions: $78,750. Investment growth accounts for over $1.3 million — the overwhelming majority of the final balance. This illustrates why starting early and never stopping is more powerful than any other variable.

Tips & Best Practices

• ✓Always contribute at least enough to capture the full employer match — it is an immediate 50-100% return on your contribution that no investment can reliably beat. Leaving match money on the table is turning down free compensation.
• ✓The 2025 IRS 401(k) contribution limit is $23,500 for employees under 50, and $31,000 for those 50 and over (including the $7,500 catch-up contribution). Maximizing your contribution in your peak earning years has an outsized compounding impact.
• ✓Increase your contribution rate by 1% each year, or automatically with each raise — you will rarely notice the smaller take-home pay, but the compounding effect over a career is enormous. A 1% increase on $75,000 is just $62.50/month pre-tax.
• ✓Asset allocation inside your 401(k) matters as much as how much you contribute: a 100% bond allocation at age 30 earning 3% instead of a diversified stock allocation earning 7% costs you hundreds of thousands in the final balance. Match allocation to your time horizon.
• ✓Avoid 401(k) loans unless absolutely necessary: while you repay yourself with interest, you lose the compounding growth on the borrowed amount, potentially pay double tax on repayments, and face immediate full taxation plus 10% penalty if you leave your job before repayment.
• ✓Vesting schedules mean your employer match may not be 100% yours immediately — a typical 3-year cliff or 6-year graded vesting schedule means leaving before fully vested forfeits some employer contributions. Factor vesting into job-change decisions.
• ✓At retirement, consider rolling your 401(k) into an IRA for more investment options and lower fees. Many company 401(k) plans have limited fund choices and higher expense ratios than what is available in a self-directed IRA.

Who Uses This Calculator

Employees deciding how much to contribute beyond the employer match to maximize retirement savings. Workers comparing the impact of starting to save at 25 versus 35. People approaching retirement checking whether their current trajectory will support their target withdrawal amount. HR professionals illustrating the long-term value of the employer match benefit to recruits. Financial advisors building retirement projections for client planning sessions.