CalcPro

401(k) Calculator

Project your 401(k) balance including the employer match.

How a 401(k) grows over time

A 401(k) is an employer-sponsored retirement account where you contribute pre-tax dollars from your paycheck, and your employer may add matching contributions. The balance grows through investment returns (typically in mutual funds or target-date funds you select). This calculator projects your future balance by combining your annual contributions, employer match, and compound investment growth.

The power of a 401(k) lies in three components: your contributions, your employer's free match, and decades of investment returns. Even small contributions grow significantly when compounded over 20, 30, or 40 years. The employer match is particularly valuable—it's immediate extra return on your contribution.

The formula

FV = (Annual Contribution + Employer Match) × [((1 + r)^n − 1) / r] × (1 + r)

Where:

  • Annual Contribution = Salary × Your contribution %
  • Employer Match = Salary × Employer match % (usually capped at your contribution %)
  • r = Expected annual return (as a decimal)
  • n = Number of years
  • FV = Future value of your 401(k)

This formula assumes contributions and salary remain constant, and returns compound annually. In reality, salaries typically increase, which would boost the balance further.

Worked example

Let's project a 401(k) for someone with these details:

  • Annual salary: $75,000
  • Your contribution: 6%
  • Employer match: 4% (they match dollar-for-dollar up to 4%)
  • Expected return: 7% per year
  • Years to retirement: 25 years

Step 1: Calculate annual contributions

  • Your annual contribution: $75,000 × 6% = $4,500
  • Employer match: $75,000 × 4% = $3,000
  • Total added each year: $7,500

Step 2: Apply compound growth Using the formula with r = 0.07 and n = 25:

  • Growth factor: [((1.07)^25 − 1) / 0.07] × 1.07 ≈ 63.25
  • Future value: $7,500 × 63.25 ≈ $474,375

After 25 years of contributions and 7% annual returns, your 401(k) balance reaches approximately $474,000. Of this, you contributed $112,500 (6% × $75,000 × 25 years), your employer added $75,000 (4% × $75,000 × 25 years), and the remaining ~$287,000 came from investment growth.

Tips for maximizing your 401(k)

Capture the full match: If your employer offers a match, contribute at least enough to receive it all. Leaving free money on the table is leaving retirement savings on the table.

Increase contributions with raises: Whenever you get a salary increase, boost your 401(k) contribution by a percentage of that raise. You'll barely notice the difference in take-home pay, but your retirement balance will grow significantly.

Review your investment allocation: Your 401(k) balance depends partly on the funds you choose. Younger workers can typically afford more stock exposure (higher risk, higher long-term returns); those nearing retirement may shift toward bonds (lower volatility).

Adjust your return assumption: If you're uncertain about the 7% figure, run the calculator with 5% and 9% to see a realistic range. Market returns vary year to year, so a range is more honest than a single number.

This calculator provides an estimate based on your inputs and assumptions. It does not account for salary increases, tax implications, or changes in contribution rates. Consult a financial advisor for personalized retirement planning.

Frequently asked questions

What is an employer match in a 401(k)?

An employer match is free money your employer contributes to your 401(k) based on what you contribute. For example, if your employer offers a 100% match up to 3% of salary, and you earn $60,000 and contribute 3% ($1,800), your employer adds another $1,800. You only get this match if you contribute—it's not automatic.

How much should I contribute to my 401(k)?

A common strategy is to contribute enough to capture your full employer match (free money), then increase contributions over time. In 2024, the IRS limit is $23,500/year for those under 50. Many financial advisors suggest aiming for 10–15% of gross salary for retirement security, but start with what fits your budget.

What return rate should I use?

This depends on your investment mix. A diversified portfolio with stocks and bonds historically averages 7–8% annually over long periods. Conservative portfolios (more bonds) may average 5–6%; aggressive portfolios (mostly stocks) 8–10%. Use a rate matching your risk tolerance and time horizon.

Does this calculator account for taxes?

No. This shows your pre-tax 401(k) balance growth. When you withdraw in retirement, withdrawals are taxed as ordinary income. Roth 401(k)s grow tax-free, but contributions are made with after-tax dollars. Consult a tax professional for your specific situation.

Can I change my contribution rate mid-career?

Yes. You can adjust your contribution percentage whenever you want (usually during open enrollment or after a life event). This calculator shows one scenario; run it again with different rates to see how changes affect your balance.

What happens to employer match if I leave my job?

Employer contributions vest over time—typically 3–5 years. Once vested, the match is yours to keep even if you leave. Unvested match is forfeited. Check your plan's vesting schedule; you can roll your balance to an IRA or new employer's plan.

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