401(k) calculator

What this projection models

A 401(k) is an employer-sponsored retirement account funded straight from your paycheck, usually pre-tax, where it grows tax-deferred until you withdraw it in retirement. This calculator takes your salary, your contribution as a percentage of it, and your employer's match percentage, converts the combined annual contribution into a monthly figure, and compounds it — together with your current balance — at the return you set over your years to retirement. Both your own contributions and the match are invested every month, which is why the final number grows so much faster than the sum of what you personally put in.

The employer match is free money

The single most important lever here is the match. A typical "50% up to 6%" arrangement means that if you contribute 6% of salary, your employer adds 3% — an instant 50% return on those dollars before the market does anything. Contributing less than the amount needed to capture the full match is leaving guaranteed money on the table, which is why it is almost always the first dollar of retirement saving to prioritise. Try setting your contribution to just below versus at the full-match threshold and watch how much the ending balance jumps; that gap is the cost of under-contributing.

Limits, taxes and what's left out

This is a pre-tax projection at a constant return, and it deliberately does not enforce the annual IRS contribution limit — real plans cap how much you and your employer can add each year, and that limit rises over time. Returns also vary year to year rather than holding flat, and traditional 401(k) withdrawals are taxed as ordinary income in retirement. To weigh tax-free growth alongside it, compare a Roth IRA, and to see when the balance could fund financial independence, use the FIRE calculator.

Educational tool only — not financial advice. A pre-tax projection that does not enforce IRS contribution limits; returns vary.