Comprehensive Guide
Learn more in our Investing Guide.
How it works
A 401(k) builds wealth three ways at once — your contributions, the employer match, and compounding — and this calculator projects all three to your retirement year. Your contribution is a percentage of salary, deferred before tax. The employer match adds their percentage on the slice of salary up to the match limit: a common 50% match on the first 6% means contributing 6% of an $85,000 salary pulls in a free $2,550 a year. The calculator compounds your current balance plus every monthly contribution at your return rate across the years, and separates the ending balance into what you put in, what the employer added, and what growth produced. On typical inputs the growth bar eventually overtakes both contribution bars combined — compounding doing most of the work, which is the entire argument for starting early. Two things to hold onto. The employer match is the only guaranteed instant return in investing — a 50% match is a 50% gain before the market moves, so contributing below the match limit leaves part of your compensation unclaimed. And the projection holds salary flat, which understates reality since contributions rise with every raise — treat the ending balance as a floor, not a ceiling.Formula
FV of balance + monthly (your % + matched %) contributions at the return rate over the years
Tips
- Contribute at least enough to capture the full employer match — it is free money.
- A 50% match is an instant 50% return before the market moves.
- Growth eventually overtakes contributions — starting early is the whole game.
- Salary is held flat, so the real balance will likely be higher — a floor, not a ceiling.
- IRS dollar limits cap high percentages — check the ceiling if you contribute a lot.
Frequently asked questions
How much will my 401(k) grow?
It depends on contributions, the employer match, years and return. With a $85,000 salary, 10% contribution, a 50% match on 6%, a $40,000 balance and 25 years at 7%, the projected balance approaches seven figures — with growth eventually exceeding everything paid in.
How does the 401(k) employer match work?
The employer adds a percentage of what you contribute, up to a slice of your salary. A 50% match on the first 6% means contributing 6% of an $85,000 salary earns a free $2,550 a year. Contributing below the limit leaves part of your compensation unclaimed.
Should I contribute enough to get the full match?
Almost always yes. The match is the only guaranteed instant return in investing — a 50% match is a 50% gain on that money before the market moves. Capturing the full match comes ahead of nearly every other financial priority after a small emergency fund.
What return should I assume for a 401(k)?
About 7% for a diversified stock-heavy portfolio after inflation is a reasonable planning figure; the nominal historical average is near 10%. Use a lower figure for a more conservative mix. The projection is a plan, not a promise.
Does the calculator account for IRS contribution limits?
It models percentages of salary, not the IRS dollar ceiling, which caps annual deferrals and adjusts with inflation. For most savers the percentage is well under the limit, but high earners contributing a large percentage should check the current dollar cap.