401k Growth Calculator
Project your 401k balance at retirement with employer match, compound growth, and annual salary increases. See how your contributions grow over time with a year-by-year breakdown.
How 401k Growth Works
A 401k retirement account grows through three powerful mechanisms: your contributions, employer matching, and compound investment returns. Each paycheck, a percentage of your pre-tax salary goes into your 401k. Your employer may match a portion of your contributions, essentially giving you free money. The combined balance then earns investment returns that compound year after year.
Compound growth is the real engine behind 401k wealth building. When your investments earn returns, those returns themselves earn returns in subsequent years. Over a 30-year career, compound growth typically accounts for more than half of your total 401k balance, making it crucial to start contributing as early as possible.
401k Contribution Limits 2025-2026
The IRS sets annual contribution limits for 401k plans. For 2025, the employee contribution limit is $23,500. If you are age 50 or older, you can make an additional catch-up contribution of $7,500, bringing your total to $31,000. Starting in 2025, the SECURE 2.0 Act introduced a super catch-up for workers aged 60-63, allowing an extra $11,250 instead of the standard $7,500.
Employer matching contributions do not count toward your employee contribution limit. The combined employee plus employer limit is $70,000 for 2025. These limits typically increase each year with inflation adjustments announced by the IRS in the fall.
Maximizing Your 401k Returns
The single most important step is to contribute at least enough to capture your full employer match. If your employer matches 50% of contributions up to 6% of salary, you should contribute at minimum 6% to avoid leaving free money on the table. After capturing the full match, consider increasing your contribution rate by 1% each year, which is barely noticeable in your paycheck but adds significantly to your retirement balance.
Asset allocation also matters. Younger workers can typically afford more aggressive stock-heavy portfolios since they have decades to recover from downturns. As you approach retirement, gradually shifting toward bonds and stable value funds helps protect your accumulated savings. Most 401k plans offer target-date funds that handle this rebalancing automatically.
401k vs Roth 401k vs IRA
A traditional 401k uses pre-tax dollars, reducing your taxable income now but requiring you to pay taxes on withdrawals in retirement. A Roth 401k uses after-tax dollars with no upfront tax break, but qualified withdrawals in retirement are completely tax-free. If you expect to be in a higher tax bracket in retirement, Roth may be better. If you expect lower income in retirement, traditional makes more sense.
An IRA (Individual Retirement Account) is a separate retirement account you open yourself, with a lower contribution limit of $7,000 for 2025 ($8,000 if age 50+). Many workers use both a 401k and an IRA for maximum tax-advantaged savings. The best strategy depends on your current tax bracket, expected retirement income, and whether your employer offers a match.