401K Calculator Guide
An employer 401(k) match is one of the few genuinely "free money" opportunities in personal finance, yet a meaningful share of workers don't contribute enough to claim the full match they're offered. Understanding how matching actually works makes it obvious why that's worth fixing first, before optimizing anything else in a retirement plan.
How Matching Formulas Actually Work
A common format is something like "50% match on the first 6% of salary you contribute" — meaning if you contribute 6% of your paycheck, your employer adds another 3% on top, for free. Contributing less than the match threshold means leaving part of that free contribution unclaimed; contributing more than the threshold is still good for your savings, but the extra amount above the threshold isn't matched. The 401(k) calculator lets you see exactly how much employer money you're capturing (or leaving behind) at different contribution percentages.
Vesting: The Match You Haven't Fully Earned Yet
Some employers use a vesting schedule, meaning you only keep 100% of the matched funds (not your own contributions, which are always yours) after a certain number of years with the company. Leaving before you're fully vested can mean forfeiting some or all of the employer-contributed portion. This detail isn't something a calculator can know about your specific plan, so it's worth checking your plan documents if you're weighing a job change.
Contribution Limits Change Every Year
The IRS adjusts how much you're allowed to contribute to a 401(k) annually for inflation, plus an additional "catch-up" amount for those 50 and older. Because these limits shift most years, treat any specific dollar figure as a snapshot rather than a permanent rule, and confirm the current limit before assuming you have room to contribute more.