Reckonary / Finance / 401(k)

401(k) calculator

401(k) growthmonthly compounding
7%
30

Balance at retirement

$996,143
Your contributions$180,000
Employer match$90,000
Investment growth$716,143

A 401(k) is a workplace retirement account where your contributions are invested and grow over time. The power of the account comes from three things working together: the money you already have, the money you add every month, and any match your employer puts in on top. Use this calculator to project what those pieces could grow into by the time you retire.

How this calculator works

It compounds monthly. Each month your balance earns one twelfth of the annual return you choose, then your contribution and the employer match are added for the next month to grow on. The headline figure is your projected balance at retirement. Below it, the ledger bar splits the total into the money you and your employer put in versus the growth that compounding added on top.

An example

Start with $10,000, contribute $500 a month, and assume your employer adds $250 a month at a 7% annual return for 30 years. You put in $180,000 of your own money and your employer adds $90,000, yet the balance lands far higher — most of that gap is investment growth. The longer the horizon, the larger that growth slice becomes relative to what you actually contributed.

Why the employer match matters

An employer match is money added to your account at no cost to you, and it compounds for as long as it stays invested. Contributing at least enough to capture the full match is one of the simplest ways to increase your retirement balance, which is why the calculator treats the match as a separate input you can adjust.

Good to know

  • Contributions and the match are added at the end of each month.
  • The return is a steady annual estimate — real markets rise and fall year to year.
  • Results ignore taxes, fees, inflation, and annual contribution limits.

Frequently asked questions

Does this include my employer match?

Yes. Enter the dollar amount your employer adds each month and it is invested alongside your own contribution, so the match compounds too.

What return rate should I assume?

Many people use a long-run stock market figure near 7% after inflation, but real returns swing year to year. Try a range to see a cautious and an optimistic case.

Does it account for contribution limits or taxes?

No. It does not enforce the annual 401(k) limit or model taxes and fees, so the balance shown is a gross before-tax estimate of growth.

How is the balance compounded?

Monthly. Each month your balance earns one twelfth of the annual return, then your contribution and the employer match are added.

Last reviewed June 2026. This tool is for education, not financial advice.