401(k) Calculator

Projecting Your 401(k) Toward Retirement

The 401(k) calculator above answers one practical question: if you keep saving at your current rate, how much could your account hold by the time you retire? It combines your current balance, your annual contribution, and your employer's matching contribution, then projects the total forward using compound growth with a growing contribution amount. Along the way it shows what that future balance would be worth in today's purchasing power after inflation, and how much monthly income it could roughly support in retirement. The numbers are a planning model rather than a guarantee, but they are an excellent starting point for deciding how much of each paycheck belongs in your retirement plan.

What Is a 401(k) and How Does It Work?

A 401(k) is an employer-sponsored retirement account in the United States, named after the section of the tax code that created it. Employees authorize a percentage of their pay to be deposited into the plan before income tax on that money is computed. This creates three important effects. First, contributions immediately reduce the taxable income reported each year, so the saver pays less income tax today. Second, the money inside the plan grows without annual taxes on dividends, interest, or capital gains, which is precisely what lets compounding work at its best. Third, taxes are deferred until money is actually withdrawn, usually during retirement when a person's income and tax bracket are typically lower than during their working years.

Many employers add a matching contribution, effectively paying extra money into the plan based on what the employee saves. Since the tax advantage of a 401(k) is already substantial, and matching turns saving into free money, financial planners almost universally rank "capture the full employer match" among the very first priorities for anyone deciding how to spend their income.

Inputs Used by This Calculator

• Current age and expected retirement age define the investment horizon, measured in years, over which growth compounds.
• Current annual salary sets the base on which your contribution percentage is applied.
• Current 401(k) balance is the lump sum already working for you that continues to grow untouched.
• Contribution percentage is the share of pre-tax salary you plan to save each year.
• Employer match percentage and match limit model how much your employer adds and up to what point.
• Expected annual salary increase grows the dollar size of your contributions over time.
• Expected annual return is the growth rate you assume for a diversified portfolio.
• Expected inflation rate corrects future balances back into today's purchasing power.

None of these values needs to be exact. The calculator is designed to be rerun: push the return slider down for a conservative view, push your contribution percentage up, and watch the projected balance respond. That short sensitivity exercise quickly reveals how much of your retirement outcome is shaped by your own behavior rather than by market luck.

How the Projection Is Computed

The engine behind the calculator is standard compound-interest mathematics. Let r be the annual return rate, g the annual salary growth rate, and n the number of years until retirement. Three pieces are added together:

The current balance, which compounds on itself for the full n years.

Your own annual contributions. Since the contribution is a fixed percentage of salary, the dollar amount rises every year the pay rises, so the stream is not an ordinary fixed annuity but a growing one. The future value of a growing annuity is the first-year contribution multiplied by the factor ((1 + r) to the power of n, minus (1 + g) to the power of n), all divided by (r - g).

Your employer's annual match participates in the same growing-annuity factor, because matches are typically percentage-based on the same rising salary.

Because outputs such as the inflation-adjusted value and the 4 percent rule withdrawal are derived from the same projected balance, the calculator simply reruns the same model to obtain them. Annual compounding and end-of-year contributions are assumed; real plans accumulate on each pay date, but the annual model stays close over multi-decade horizons and leans slightly conservative, which is the safe direction when planning.

A Worked Example, Step by Step

To make the model concrete, consider a 30-year-old earning 60,000 per year with an existing balance of 10,000. They contribute 6 percent of salary, their employer matches half of the contribution up to 6 percent of pay, and retirement is planned at 65. Assumptions: salary grows 3 percent a year, the portfolio earns 7 percent a year, and inflation runs at 3 percent.

The horizon n equals 35 years. The first-year employee contribution is 3,600 and the first-year match is 1,800. Compounding the starting balance for 35 years at 7 percent multiplies it by about 10.68, taking the 10,000 to roughly 107,000. The growing-annuity factor for 35 years at 7 percent return and 3 percent growth is about 196, so the contribution stream becomes approximately 3,600 times 196, near 706,000, and the match stream adds another 353,000. The total lands close to 1.17 million.

Inflation, however, discounts that promise. Dividing by the 3 percent inflation compounding over 35 years, the balance's purchasing power in today's dollars is roughly 415,000. And a withdrawal based on the 4 percent rule takes about 4 percent of the balance in the first retirement year, which translates to roughly 3,900 per month. Notice how different the headline million and the real spending-power figure are; any credible retirement plan should show you both.

The Employer Match Is Free Money

A 401(k) match is best understood as extra compensation. In the example above, the 50 percent match up to 6 percent of salary contributes 1,800 a year, which is effectively a guaranteed 3 percent raise, and it keeps paying for the whole career. Run the calculator once with the match and once without, and the difference in the projected balance will typically be around 25 to 30 percent, more at longer horizons. Employers design matches mainly as a retention tool, but the participant sees the mechanical benefit: matching should be treated as an unmissable part of your compensation.

Two matching shapes are common. A percentage match, such as 50 percent of contributions up to 6 percent of salary, caps the employer gift at 3 percent of pay. A dollar-for-dollar match matches the first several percent of contributions 100 percent. The calculator handles both with the same pair of inputs, matching the match share and the cap, and applies the cap to the lower of your contribution rate and the limit so the model stays faithful to how plans actually pay.

Why the Inflation-Adjusted Number Matters

Inflation is the slow erosion of what money buys. At a steady 3 percent, prices double every 24 years, which is shorter than most retirement horizons. The inflation-adjusted output discounts the full projection back by your inflation assumption, letting you compare the future balance against the lifestyle costs you actually know today. Retirement income planning basically requires this correction, especially for people reading their plan in their twenties or thirties, when the gap between nominal and real value is at its widest.

Withdrawals and the 4 Percent Rule

Retirement does not usually mean a single lump sum; it means a stream of withdrawals that needs to last decades. The 4 percent rule is a well-known guideline: withdraw roughly 4 percent of the account in the first year and then grow the dollar amount with inflation, a pattern that historically survived 30-year periods in most market sequences. The monthly withdrawal output divides the 4 percent annual figure by twelve, so a retiree with 1.17 million would see roughly 46,800 a year, or about 3,900 per month, before tax.

Note that distributions from a traditional 401(k) are ordinary income, so the net amount is what remains after income tax at retirement-bracket rates. The rule also says nothing about sequence-of-returns risk, so anyone retiring into a severe bear market often uses a more conservative first-year rate, or keeps two or three years of expenses in cash to avoid selling at the bottom.

The Real Cost of Early Withdrawals

Because the whole point of a 401(k) is tax-deferred compounding, taking money out early is deliberately expensive. Distributions before age 59.5 normally face regular income tax plus a 10 percent additional penalty, and the money pulled no longer compounds. Assume your marginal tax rate is 22 percent: a 20,000 early withdrawal costs 2,000 in penalty plus 4,400 in tax, leaving roughly half the original intent. Exceptions exist, such as hardship cases, disability, unreimbursed medical costs, or a separation of employment occurring in or after the year you turn 55, but each exception has its own fine print.

The better friends of an early-withdrawal decision are rollovers. Moving a 401(k) into an IRA keeps the tax-deferred status, avoids penalties when done properly, and usually expands the menu of investments far beyond a single plan's funds. Because a rollover is not a distribution if executed correctly, it is almost always preferable to cashing out.

Keeping an Eye on IRS Limits

Congress sets an annual dollar cap on employee deferrals, 24,500 in 2026, with higher catch-up amounts for savers aged 50 and above. A person deferring a high percentage of a large salary can hit that cap before year-end, which can matter for match timing in some plans. The calculator does not clamp contributions at the cap; adding that ceiling would silently distort the projection for high earners, so the tool instead shows the raw compounding. If your deferrals near the cap, adjust the contribution percentage near mid-year or direct excess savings to a plan that can accept it.

Ideas for Using Your Results

• Set a target balance first, then work backwards to find the contribution percentage that reaches it.
• Test the impact different ages, 65 versus 70, and see how much an extra five years accumulates.
• Compare 5, 7, and 9 percent returns to see how heavily the outcome depends on the market, which argues for long-term diversified holdings.
• Revisit the projection each time salary or match terms change; a projection is a living estimate, not a fixed promise.

This calculator works best alongside the site's retirement planner for income goals, the Roth calculators for tax-strategy comparison, and a compound interest guide for a deeper feel for how a periodic dollar ages. However the scenario plays out, the durable lessons remain unchanged: start early, capture the match, hold the course, and let compounding deliver the largest share of the result.

Disclaimer

Results are provided as estimates for informational purposes only and may be inaccurate. Always verify outcomes with a qualified professional before making financial or personal decisions based on these calculations.