What is the 401K Calculator?

The 401K Calculator is a free online tool that helps you calculate results instantly. Enter your values above and click Calculate to see results.

Is the 401K Calculator free?

Yes, the 401K Calculator is completely free to use with no registration required. You can use it as many times as you need on any device.

How accurate is this calculator?

Our 401K Calculator uses standard formulas for accurate results. For critical decisions, always verify with a qualified professional.

401(k) Calculator

Estimate how your 401(k) will grow by retirement. Enter your current balance, annual contributions, employer match, and expected rate of return to see your projected nest egg — including a breakdown of your contributions, employer match, and investment gains.

401(k) Retirement Growth Calculator

Current Age

Retirement Age

Current Balance ($)

Annual Contribution ($)

Employer Match (%)

Match Limit (% of salary)

Annual Salary ($)

Expected Return (% /yr)

How 401(k) Growth Works

Your 401(k) balance grows through three sources: your own contributions, your employer's matching contributions, and investment returns compounding over time. The formula used is:

FV = P·(1+r)ⁿ + C·((1+r)ⁿ − 1)/r

Where P = current balance, C = total annual contribution (yours + employer match), r = annual return rate, n = years to retirement.

IRS 401(k) Limit (2024)	Amount
Employee contribution limit	$23,000
Catch-up contribution (age 50+)	+$7,500
Total including employer contributions	$69,000
Common employer match	50%–100% up to 3–6% of salary

Frequently Asked Questions

How does employer matching work?+

Employer matching means your company contributes to your 401(k) based on your own contributions. A common formula is "50% match up to 6% of your salary" — meaning if you earn $75,000 and contribute at least $4,500 (6%), your employer adds $2,250 (50% of $4,500). Always contribute at least enough to capture the full employer match — it's free money.

What return rate should I use?+

A common assumption is 6–8% per year for a diversified stock/bond portfolio over the long term. The S&P 500 has historically averaged about 10% annually before inflation, and roughly 7% after inflation. Use a more conservative rate (5–6%) for longer time horizons or more bond-heavy allocations. Remember: past performance does not guarantee future results.

How Investment Growth Is Calculated

Investment accounts grow through compound interest — your returns earn returns. Unlike simple interest (where you only earn on the principal), compounding means that every dollar of gain becomes part of the base that earns the next round of gains. The longer the time horizon, the more dramatic the effect.

The Compound Interest Formula

A = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) − 1) / (r/n)]

P = Starting balance (principal)
r = Annual interest rate (as a decimal)
n = Compounding frequency (12 for monthly)
t = Time in years
PMT = Regular monthly contribution

How to Use This Calculator

Enter your starting balance (or $0 if starting from scratch)
Enter your expected annual return rate (7–10% is a common long-term stock market assumption)
Enter your monthly contribution
Set the number of years until you plan to withdraw
Click Calculate to see projected balance and growth breakdown

The Power of Starting Early

Investing $300/month starting at age 25 at 8% annual return gives you ~$1,006,000 by age 65.

Starting at 35 with the same $300/month: ~$440,000 — less than half, even though you only missed 10 years.

Those 10 years cost you $566,000 in future value, even though the missed contributions were only $36,000. That gap is the compounding effect in action.

Important Caveats

Investment returns are not guaranteed. Stock market returns vary year to year — 8% is a long-term historical average for diversified index funds, not a promise. Tax-advantaged accounts (401k, IRA, Roth IRA) shelter gains from annual taxation, which can significantly increase real returns compared to a taxable brokerage account.