401(k) Calculator

A 401(k) is a retirement account offered by many US employers. You choose a percentage of pay to put in, often through payroll deduction, and many employers add a match. Because the money compounds for decades, small changes today, such as contributing enough to get the full match, can change the final balance a great deal. This page projects the balance and shows how much came from you, your employer and growth.

The yearly steps

For each year until retirement the page does the same things. It takes your salary times your contribution percentage, trims it to the yearly limit, and works out the match: the match rate times your contribution, but only on the part up to the percentage of salary where the match stops. It adds both to the account, lets the whole balance earn the return you enter, and raises the salary by your yearly raise. The table prints the balance every five years.

The limit

The yearly limit on your own contributions is a field, set to 23,500, the IRS figure for 2025. Catch-up contributions after age 50, which the field hint mentions, are not added automatically; raise the limit field if you want to include them. If your chosen percentage would exceed the limit, the page caps your contribution and shows a warning that the limit is assumed to stay flat, although in practice it rises over time.

A worked example

The default is a 35-year-old with 45,000 saved, a salary of 90,000 rising 3 percent a year, contributing 8 percent with a 50 percent match up to 6 percent, a 7 percent return, 2.5 percent inflation and retirement at 65. The balance at 65 is 1,670,752. Your contributions total 342,543, the employer match 128,454, and growth 1,154,756. In today’s money the balance is 796,519, and 4 percent of that is 31,861 a year. In the first year the match is 2,700. In the second sample, a 40-year-old with 150,000 saved, a 120,000 salary, a 15 percent contribution and a 100 percent match up to 4 percent, the balance is 2,640,224, and the warning appears because the contribution reaches the limit.

The match

The match is the easiest return to capture, since it is paid the moment you contribute. In the default case, raising the contribution from 4 percent to 6 percent increases the match, while going above 6 percent adds none. Check your plan’s actual formula, as some use a tiered match and some pay a flat percentage of pay, and set the three match fields to approximate it.

Reading the 4 percent figure

The 4 percent line is a common rule of thumb for a first-year withdrawal, not a promise, and the page labels it that way. Taxes on withdrawals are not deducted. Social Security and other income are not included either, so this is only one part of a retirement plan.

Edge cases

The retirement age must be after the current age. A return below zero is allowed to test a bad decade. A match rate over 100 percent is accepted up to 300 percent. Zero salary is rejected. A contribution percentage of zero shows no match, because the match depends on contributing.

Limits

Fees, early withdrawal penalties, loans, required minimum distributions, employer contributions that are not a match and vesting schedules are not modelled. A constant return is a simplification, since real markets vary from year to year. Whether a contribution is pre-tax or Roth changes the taxes at withdrawal but not the pre-tax growth shown here.

Related tools

• Retirement and FIRE Calculator tests whether a balance supports your target income.
• Compound Interest Calculator isolates the growth of a single deposit.
• 1099 Tax Calculator covers the self-employed, who have no employer match.
• Inflation Calculator converts future dollars into today’s purchasing power.