401(k) Retirement Savings Calculator

Your yearly 401(k) contribution (up to $23,000 in 2024)
Number of years until retirement
Expected annual investment return (historical stock market ~7-10%)
Finance

This 401(k) calculator estimates how large your retirement account could grow by the time you retire. Enter your annual contribution, the number of years until retirement, and an expected annual return, and it projects your balance using the future value of an annuity, splitting the total into what you contributed and what your investments earned.

Formula

FV = PMT × [((1 + r)^n - 1) / r]
  • The projection uses the future value of an ordinary annuity: FV = PMT × [((1 + r)ⁿ − 1) / r], where PMT is the annual contribution, r the annual return, and n the number of years.
  • Total contributions are simply PMT × n; investment gains are the projected balance minus what you put in.
  • Compounding does the heavy lifting: the longer your money stays invested, the larger the share of the balance that comes from gains rather than contributions.
  • Enter the return as a plain percentage (e.g. 7 for 7%). The historical long-run stock-market return is roughly 7-10% before inflation.
  • This is a simplified estimate: it assumes a constant return, level contributions, and ignores fees, taxes, and employer matching.

Example Calculation

Inputs
  • Annual Contribution: 15000
  • Years of Service: 30
  • Annual Return Rate (%): 7

Contributing $15,000 a year for 30 years at a 7% annual return gives a projected balance of about $1.42 million. Of that, $450,000 is your own contributions ($15,000 × 30) and roughly $967,000 is investment growth from compounding.

Frequently asked questions

How is the 401(k) balance projected?
It uses the future value of an annuity formula, FV = PMT × [((1 + r)ⁿ − 1) / r], assuming you contribute the same amount each year and earn a constant annual return.
What return rate should I assume?
A common planning assumption is 7%, reflecting the long-run average stock-market return for a typical asset mix. Use a lower figure for a more conservative estimate.
Does this include employer matching?
No. To include a match, add your employer's annual contribution to your own and enter the combined amount as the annual contribution.
Why are investment gains so large over time?
Because returns compound: each year's growth earns its own return in later years, so over decades the gains can far exceed the total you contributed.
Does it account for taxes and fees?
No. It is a gross estimate. Traditional 401(k) withdrawals are taxed later, and investment fees reduce real returns, so your net outcome will be somewhat lower.