401(k) Calculator

How a 401(k) grows your retirement

A 401(k) is an employer retirement account you fund straight from your paycheck before income tax, so every dollar you contribute lowers this year’s taxable income and then grows tax-deferred until you withdraw it in retirement. The single most valuable feature is the employer match: many employers match a percentage of what you put in, up to a share of your salary — a common formula is 50% of your contributions up to 6% of pay. That match is an immediate, guaranteed return, which is why the first rule of a 401(k) is to contribute at least enough to capture the full match. This calculator shows exactly how much of that free money you collect over a career.

The IRS limits how much you can defer each year. For 2025 the elective-deferral limit is $23,500, and workers 50 and older can add a $7,500 catch-up contribution — with an enhanced catch-up of $11,250 for ages 60 to 63 under SECURE 2.0. The calculator caps your contribution at the limit for your age and flags the years you hit it, because the employer match and any after-tax additions sit under a separate, higher total limit. Over 30 or more years, contributing steadily inside these limits and reinvesting the returns is what turns modest paychecks into a seven-figure balance.

Two levers matter most: time and the match. Starting early lets compounding do the heavy lifting — in a long projection, growth typically dwarfs the raw dollars you contribute. And never leaving the employer match on the table can be worth tens of thousands of dollars over a career. This tool models a traditional pre-tax 401(k) with a steady annual return and salary growth; it holds the current IRS limit constant and does not model taxes at withdrawal, fees, or a Roth 401(k). Treat it as a planning estimate, and revisit it as your salary, match, and the annual limits change.