401(k) Calculator United States

The 401k calculator projects where your workplace retirement account could be by the time you retire. You enter your salary, your contribution rate, your employer’s match and an expected return, and it shows the projected balance plus the income tax you defer each year by contributing pre-tax.

What the 401(k) calculator does

A 401(k) is an employer-sponsored retirement plan for workers in the United States. Part of each paycheck goes into the account before income tax is applied, your employer often adds a matching amount, and the money is invested so it can compound over decades. The calculator projects the balance that steady saving could build and shows the yearly tax break on traditional (pre-tax) contributions.

An extra percentage point of salary, or starting a year earlier, can be worth a large sum by the time you stop working, and the calculator lets you test those changes.

How the projection works

The tool combines four inputs:

• Your contributions: the share of salary you put in each pay period.
• Employer match: the amount your employer adds, usually up to a set limit.
• Investment return: an assumed average annual growth rate for the funds you hold.
• Time horizon: the number of years until you plan to retire.

Each year the calculator adds your contributions and the match, applies the assumed return to the running balance, and carries the total forward. Returns are earned on earlier returns as well as on new money, so the growth curve steepens over time, and the last years of a long career often add the most.

How to use it

1. Enter your current salary and how much of it you contribute.
2. Add your employer’s matching formula.
3. Choose an expected average annual return that fits your investment mix.
4. Set the number of years until retirement.
5. Read the projected balance and the estimated annual tax saving.

Run a few scenarios. Raise your contribution by a point or two, or push your retirement age out by a couple of years, and compare the ending balances.

How to read the result

The main figure is your projected balance at retirement. Real returns will differ from the assumption, so read it as the middle of a range. If it is lower than you hoped, the inputs you control are your contribution rate, your investment choice and your time horizon.

The annual tax saving line shows roughly how much income tax you defer this year by contributing pre-tax. You generally pay that tax when you withdraw in retirement, but many people expect to be in a lower bracket by then, and in the meantime the untaxed money stays invested.

The calculator uses the current-year contribution limits and tax rules, so use the live result instead of a figure you remember from a previous year.

Getting the most from your 401(k)

• Capture the full match first. Contributing at least enough to earn your employer’s full match is an immediate return on your money, and leaving it unclaimed is a common mistake.
• Increase contributions gradually. Raising your rate by one point each time you get a raise barely changes take-home pay but adds up over a career.
• Watch the fees. Fund expense ratios reduce returns every year, so lower-cost options leave more growth in your account.
• Revisit your mix as you age. Many savers shift from growth toward stability as retirement nears, and your return assumption should match the mix you hold.

Why starting early matters

Time is often the input people overlook. Contributions made early in a career have decades to compound, while late contributions have only a few years. Two savers who put away the same total can end up with very different balances because one started earlier.

You can see this by changing the time horizon. Add years to retirement and the projected balance rises by far more than the extra contributions alone. Remove years and it falls sharply. A small contribution started early often ends up ahead of a larger one started a decade later, so starting now at a rate you can sustain, and raising it over time, usually beats waiting for a higher salary.

How the 401(k) fits your wider plan

Most people have other retirement money too: an IRA, taxable investments, and expected Social Security income. Read the projected balance alongside those sources.

It also helps to turn the balance into income. In retirement what you live on is the income the balance can sustain year after year, so think about the lifestyle it could support, and re-run the projection as your salary, savings rate and goals change.

Common mistakes to avoid

• Assuming an unrealistic return. Optimistic growth rates inflate the projection, so choose a conservative long-run average.
• Ignoring inflation. A future balance buys less than the same number today, so judge the result by the lifestyle it would fund.
• Cashing out when changing jobs. An early withdrawal can trigger tax and penalties and loses years of compounding. A rollover usually keeps the money invested.
• Never revisiting it. Salaries rise, rules change and goals shift, so re-run the calculator once a year.

This is general information, not financial advice. Confirm figures and rules with a qualified professional before making decisions.

About This 401k Calculator

Use this 401k calculator to get an instant, accurate estimate. The figures follow official IRS guidance and every rate and threshold is kept up to date for 2026. Adjust the inputs above to match your situation, or browse all our calculators to plan your next step.