401(k) Calculator

Project 401(k) balance at retirement with employer match, contribution limits, catch-up contributions, and Roth vs traditional comparison.

Tested tool guide Tested browser tools Checked August 15, 2026

What 401(k) Calculator does, with a checked example

Enter your current 401(k) balance, age, salary, contribution rate, employer match formula, and expected annual return, and the calculator compounds those inputs year by year to a projected balance at your chosen retirement age. It applies IRS elective-deferral limits and catch-up contributions once you reach the eligible age, and can split the projection into Roth (after-tax) versus traditional (pre-tax) outcomes. Because employer match is a formula you enter yourself (e.g., 50% up to 6% of salary), a mismatch between the formula you enter and your actual plan document will produce an inaccurate employer-contribution figure - check it against your plan's summary plan description before relying on the projection.

Worked example

A concrete input and expected output from the current implementation.

Input

Age 35, retire at 65 (30 years). Starting balance $0. Salary $80,000, employee contributes 6% ($4,800/yr). Employer matches 50% of the first 6% ($2,400/yr). Combined contribution $7,200/yr, made at year-end, no salary growth. Expected annual return 7%, compounded annually.

Expected output

Projected balance at 65: approximately $680,118.

This is the future value of a 30-year ordinary annuity: $7,200 x [(1.07^30 - 1) / 0.07] = $7,200 x 94.4608 = $680,118, holding contributions and return flat and ignoring raises, inflation, or fees.

How the result is produced

Year-by-year compounding with match and limits

The calculator steps forward one year at a time: it applies the assumed annual return to the running balance, then adds that year's employee and employer contributions at year-end, consistent with the year-end contribution timing used throughout the projection. It checks the employee's contribution against the current-year elective deferral limit and any catch-up allowance once you cross the eligible age; employer contributions are tracked separately toward the overall annual-additions limit rather than counted against the deferral limit. If your contribution rate would exceed the elective deferral limit, it caps the employee portion rather than letting it run past the IRS ceiling.

Roth vs traditional split

For a side-by-side comparison, the tool runs the same contribution schedule twice: once assuming pre-tax (traditional) contributions that reduce current taxable income but are taxed on withdrawal, and once assuming after-tax (Roth) contributions taxed now and tax-free at withdrawal if the distribution is qualified (a nonqualified withdrawal may include taxable earnings). It applies the tax rates you enter for today and for retirement to show which leaves more spendable money later.

Good uses

Checking whether raising your contribution percentage by a few points meaningfully changes your projected retirement balance
Confirming you're contributing enough to capture the full employer match rather than leaving part of it unclaimed
Comparing a Roth versus traditional 401(k) election before open enrollment, using your own expected tax rates now and in retirement

Limits and checks

The projection uses a single constant annual return you supply; it does not model market volatility, down years, or sequence-of-returns risk near retirement
It does not account for employer match vesting schedules or job changes, so a projected match assumes full, immediate ownership of every employer dollar
Contribution and catch-up limits are set by the IRS and adjusted most years; verify the figures the calculator is using against the current year's official limits before relying on the result

Common questions

Does it account for vesting if I leave my employer before the match is fully vested?

No. The calculator assumes every employer match dollar is fully vested and stays in your account. If your plan uses a graded or cliff vesting schedule, a job change before you're fully vested would leave you with less than the projected balance, and you'd need to adjust the employer contribution input yourself.

Does the projected balance account for inflation?

Not on its own. Entering a real (inflation-adjusted) rate of return only removes inflation's effect on investment growth; your salary, contribution amounts, and any assumed raises would also need to be entered in today's dollars for the whole projection to be in real terms. The calculator doesn't separately deduct inflation, so a result built from a nominal return and nominal salary inputs is a nominal dollar figure, not today's purchasing power.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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