How is the 401(k) balance at retirement calculated?

Each year the tool adds your contribution (salary times your contribution percent) plus the employer match, then compounds the running balance at your expected annual return. New money in a given year earns about half a year of growth (a mid-year convention), and the cycle repeats until your retirement age. Existing balance and contributions both keep compounding.

How does the employer match work?

A common formula is 50% of your contribution up to 6% of salary. That means the employer adds 50 cents for every dollar you put in, but only on the first 6% of pay. Enter the match rate and the salary cap separately so any plan shape — full match, partial match, or a different cap — can be modelled.

What is the employer match worth over time?

The match is free money, and because it is invested it also earns returns for decades. The tool runs your plan twice — once with the match and once without — and reports the difference at retirement, which is the true lifetime value of the match including all the growth it generates.

What return should I assume for a 401(k)?

There is no single right number. Many people model a long-run average of 6 to 8 percent for a diversified stock-heavy portfolio before inflation, and lower if they hold more bonds or want a conservative estimate. Try a few values to see how sensitive your projection is to the return assumption.

Am I leaving money on the table if I contribute below the match cap?

Usually yes. If your match caps at 6% of salary but you only contribute 4%, you forfeit part of the match every paycheck. The calculator flags this and shows the contribution rate that captures the full employer match.

Does this account for contribution limits, taxes or inflation?

No. It is a pre-tax growth projection in nominal terms and does not enforce annual IRS contribution limits, withdrawal taxes, fees or inflation. Treat the result as an estimate of the account balance, not spendable after-tax income, and keep statutory limits in mind when setting your contribution.

401(k) Calculator — Gera Tools

A 401(k) calculator that projects how large your retirement account could grow from four things you control or know: your salary, the percentage you contribute, your employer’s match, and the annual return you expect your investments to earn. It is for anyone deciding how much to put into their workplace plan, weighing whether a raise should go toward retirement, or simply wanting to see the long-term payoff of starting early. Crucially, it isolates one number most calculators bury: the dollar value of the employer match over your whole career, including the growth that free money earns on top of itself.

How it works

The tool runs a year-by-year simulation from your current age to your retirement age. In each year it works out three flows. Your own contribution is salary x contribution%. The employer match mirrors part of that: it matches the smaller of your contribution rate and the match cap, then multiplies by the match rate — so a “50% up to 6%” plan adds salary x 6% x 50% when you contribute at least 6%. Both amounts land in the account, the running balance compounds at your expected return, and your salary grows by the optional raise rate before the next year. New contributions are credited with roughly half a year of growth (a mid-year convention), which keeps the estimate realistic rather than over-optimistic.

To value the match, the calculator runs the same plan a second time with the match switched off and reports the gap at retirement. Because that money compounds for decades, the lifetime value of a match is almost always far larger than the raw contributions — that is the headline the green panel surfaces.

Balance each year = (opening + your contribution + employer match) compounded at your expected return.

Worked example

Suppose you are 30, earn $70,000, contribute 6%, and your employer matches 50% up to 6% of salary. You already hold $20,000 and expect a 7% annual return, retiring at 65.

You contribute about $4,200 in year one; the employer adds $2,100 on top.
After 35 years of compounding, the projected balance is roughly $900,000 in nominal terms.
Of that, the employer match plus its growth accounts for well over $200,000 — money you would have lost entirely by not contributing enough to earn it.

Contribution	Match	Retire age	Match value at retirement
3%	50% up to 6%	65	lower — you miss half the cap
6%	50% up to 6%	65	full match captured
10%	50% up to 6%	65	same match, bigger balance

Change any input and every figure, the breakdown and the chart update instantly. Every number is calculated in your browser — nothing about your salary or savings is ever uploaded or stored.