401(k) Calculator

A 401k calculator grows every month’s contribution and employer match at your expected return: balance = P(1 + i)^N + each deposit grown to retirement. For example, a $25,000 balance plus 5% of a $60,000 salary, a 50% match up to 6% of pay, 2% raises and a 5.5% return after fees grows to about $892,190.86 by age 67.

How to use the 401(k) calculator

1. Pick a tab. 401(k) balance projects your account at retirement, Roth vs traditional compares the two after tax, and Match check shows whether you collect your full employer match.
2. Enter your age, retirement age, salary, yearly raise, current balance and the percent of pay you contribute.
3. Enter your employer’s match formula. Choose Two tiers for formulas such as 100% of the first 3% of pay plus 50% of the next 2%.
4. Type your own return, fees and inflation. Open Vesting and IRS limits to set a vesting schedule or change the 2026 limits.
5. Read the balance, the split between your money, the match and growth, and the match message. Open Show steps for the full working and the table for every year.

401(k) growth formula

A 401(k) balance grows in two parts. What you have today grows as a lump sum, and each month’s deposit (your contribution plus the match) grows as an annuity:

FV = P × (1 + i)^N + C × ((1 + i)^N − 1) ÷ i

• P is your balance today.
• C is the monthly deposit: your contribution plus the employer match.
• i is the monthly return after fees: the yearly rate ÷ 12. At 6%, i = 0.005.
• N is the number of months until you retire.

Worked example. You put in $400 a month and your employer adds $200, so C = $600. At 6% a year for 30 years, N = 360 and 1.005³⁶⁰ ≈ 6.022575. The deposits grow to 600 × (6.022575 − 1) ÷ 0.005 ≈ $602,709.03, from $216,000 paid in. Your own $400 a month accounts for $401,806.02 of that, and the match for $200,903.01.

The calculator does the same thing month by month, so it can also raise your pay each year and stop your contribution at the IRS limit.

2026 401(k) contribution limits

The IRS sets the limits each year. These are the figures for tax year 2026 from IRS Notice 2025-67, which the calculator uses as its starting point.

Limits usually change for later years. The calculator holds them flat unless you enter a yearly increase, so long projections for high savers are on the cautious side.

How the employer match works

A match formula has a rate and a limit. “50% up to 6% of pay” means your employer adds 50 cents for each dollar you contribute, on contributions up to 6% of your salary. Some employers use two tiers, such as 100% of the first 3% of pay plus 50% of the next 2%.

Worked example. On a $60,000 salary with a 50% match up to 6%, the match applies to the first 0.06 × 60,000 = $3,600 you put in. Contributing 4% ($2,400) earns $1,200. Contributing 6% ($3,600) earns the full $1,800. Under the two-tier formula, contributing 5% ($3,000) earns $1,800 on the first 3% plus 50% of $1,200 on the next 2%, a $2,400 match.

The table is for a $60,000 salary. Above 6% the match stays at $1,800, so each extra dollar is yours alone.

Are you leaving 401(k) match on the table?

The SEC’s investor education site points out that an employer who adds 50 cents for every dollar you save gives you an immediate 50 percent return on that money. Contributing less than the match limit gives part of that return away. In the calculator’s example, contributing 5% instead of 6% misses $300 of match in the first year. Kept up until 67 with raises and growth, the extra 1% (your money plus the match) adds about $140,354.39 to the balance.

One timing detail: some plans work out the match each paycheck. If you reach the IRS limit early in the year, the match can stop for the rest of the year unless the plan has a “true-up”. The calculator works out the match on the whole year, so check your plan’s rules if you contribute a large share of pay.

401(k) vesting schedules

The IRS says the money you contribute from your salary is always 100% vested. Employer contributions can follow a vesting schedule set by the plan. The IRS shows two common examples:

Choose a schedule and your years with the employer, and the year-by-year table adds a “Vested” column: the amount you could keep if you left at the end of that year.

Roth vs traditional 401(k)

According to the IRS, traditional (pre-tax) contributions go in before tax and withdrawals are taxed. Designated Roth contributions go in after tax, and qualified withdrawals of contributions and earnings are not taxed. A qualified withdrawal comes at least five years after your first Roth contribution and on or after age 59½, disability or death. Both share one contribution limit, and matching contributions cannot go directly into the Roth account.

Worked example. Take $1,000 of pay, a 22% tax rate now, 15% in retirement and 6% a year for 30 years (1.06³⁰ ≈ 5.743491). Traditional: all $1,000 goes in and grows to $5,743.49; after 15% tax you keep $4,881.97. Roth: tax comes first, so $780 goes in and grows to $4,479.92, tax-free. Traditional wins here because the retirement rate is lower. With equal rates the two come out the same.

The Roth tab compares the same contribution percent both ways. To keep the take-home cost equal, it assumes the traditional saver invests each year’s tax saving in a taxable account. It then shows the break-even retirement tax rate. These are estimates with tax rates you choose, not tax advice.

Common 401(k) calculation mistakes

• Using a return before fees. A 0.5% yearly fee on a 6% return leaves 5.5%, which matters over decades.
• Counting the match on your whole contribution when it stops at a percent of pay.
• Forgetting that the IRS limit caps contributions, including catch-up rules from age 50 and the higher catch-up at 60 to 63.
• Comparing Roth and traditional balances without taxes. A traditional balance is before tax; a qualified Roth balance is after tax.
• Reading a future-dollar balance as today’s buying power. Divide by (1 + inflation)^years, as the calculator does.

These results are estimates for planning and learning, not financial or tax advice.

Sources

Checked November 2026.

• IRS Notice 2025-67, 2026 Amounts Relating to Retirement Plans and IRAs
• IRS, 401(k) limit increases to $24,500 for 2026
• IRS, Retirement topics: 401(k) and profit-sharing plan contribution limits
• IRS, Retirement topics: Vesting
• IRS, Roth comparison chart
• IRS, Retirement topics: Designated Roth account
• SEC Investor.gov, Free Money!

401(k) savings practice quiz: 10 questions

Test yourself with 10 multiple-choice questions. Choose an answer and press Submit to see if you are right and why. Your score appears at the end.

Frequently asked questions

How much will my 401(k) be worth when I retire?

It depends on your balance, contribution rate, match, raises, return after fees and years to retirement. In the example, $25,000 plus 5% of a $60,000 salary with a 50% match grows to about $892,190.86 by 67 at 5.5% after fees, or about $298,868.71 in today's dollars with 3% inflation.

What is the 401(k) contribution limit for 2026?

$24,500 for employee contributions, plus an $8,000 catch-up at age 50 or older, or $11,250 at ages 60 to 63. Your contributions plus employer money cannot exceed $72,000, not counting catch-ups.

What is a good 401(k) match?

Compare formulas by the most match you can get as a percent of pay. A 50% match up to 6% is worth up to 3% of pay; 100% of the first 3% plus 50% of the next 2% is worth up to 4%. Then contribute at least enough to collect all of it.

Should I choose a Roth or traditional 401(k)?

If you pay the same tax rate now and in retirement, they come out about even. A traditional 401(k) tends to win if your rate will be lower in retirement, and Roth if it will be higher. The Roth tab shows the break-even rate for your numbers.

What happens to my employer match if I leave before I am vested?

You keep all of your own contributions and their growth. You keep only the vested share of employer money; the rest goes back to the plan. Under a 6-year graded schedule, leaving after 3 years keeps 40% of the match.

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