This 401k calculator projects how your retirement account grows from today until the day you stop working. It combines the three engines of a 401k — your own contributions, your employer’s matching dollars, and compound investment returns — and shows exactly how much each one adds to your final balance.
Enter your age, salary, contribution percentage, and your employer’s match terms. The year-by-year table reveals the pattern every long-term saver should see: contributions dominate early on, but after a decade or two, investment growth becomes the largest force in the account.
How the Projection Works
Each year the calculator repeats four steps:
- Your contribution = salary × your contribution percentage
- Employer match = (match rate) × your contribution, but only on contributions up to the match limit (e.g. 50% match up to 6% of salary means a maximum match of 3% of pay)
- The balance grows by the assumed annual return, then the year’s contributions are added
- Salary increases by the salary growth rate for the following year
The default 7% return reflects a stock-heavy portfolio’s historical average after fees; the S&P 500 has returned about 10% annually before inflation over the long run. Lower the return assumption if your portfolio is bond-heavy or you want a conservative estimate.
Contribution Limits and the Employer Match
The IRS caps how much you can defer into a 401k each year, and the limits change annually with inflation. For 2025 the employee deferral limit was $23,500, with an extra $7,500 catch-up for those 50 and older (and a higher catch-up for ages 60–63). Always verify the current year’s limits on IRS.gov before setting your contribution rate.
Key guidance:
- Always contribute at least enough to capture the full employer match — a 50% match is an instant 50% return
- The most common match formula is 50 cents per dollar up to 6% of salary
- Employer match dollars do not count against your employee deferral limit; a separate, higher combined limit applies
- Raise your contribution rate by 1% each year or with every raise to reach the cap painlessly
Example: 30-Year-Old Earning $70,000
Take the calculator defaults: age 30, retiring at 65, a $25,000 starting balance, $70,000 salary, contributing 8% with a 50% employer match up to 6% of salary, 7% returns, and 3% annual raises.
- Year one: you contribute $5,600 and your employer adds $2,100 (50% of the 6% matched portion)
- Over 35 years you contribute about $338,000 and your employer adds about $127,000
- Compound growth contributes roughly $1.29 million more
The projected balance at 65 is about $1.78 million — and over 70% of it is investment growth, not money anyone deposited. Starting the same plan at 40 instead of 30 yields only about $780,000, cutting the final balance by more than half.
Frequently Asked Questions
How much should I contribute to my 401k?
A common target is 15% of gross income toward retirement, including the employer match. At minimum, contribute enough to earn the full match — skipping a 50% match up to 6% of salary leaves 3% of your pay on the table every year.
What is the 401k contribution limit?
For 2025 the employee deferral limit was $23,500, plus a $7,500 catch-up for workers 50 and older. Limits adjust with inflation most years, so check the current IRS announcement before maxing out. Employer matching contributions are subject to a separate, higher combined limit.
How does a 401k employer match work?
Your employer contributes extra money based on what you contribute. The most common formula is 50% of your contributions up to 6% of your salary: if you earn $70,000 and contribute at least 6% ($4,200), your employer adds $2,100. Contribute less and you receive proportionally less match.
What rate of return should I assume for my 401k?
A 7% annual return is a reasonable long-term assumption for a diversified, stock-heavy portfolio after fees, based on roughly 10% historical stock market averages minus typical costs and some conservatism. Use 5–6% for balanced portfolios or if you prefer a cautious projection.
What is the difference between a traditional and Roth 401k?
Traditional 401k contributions are pre-tax — they reduce taxable income now, but withdrawals in retirement are taxed as ordinary income. Roth 401k contributions are made after tax, and qualified withdrawals, including all growth, are tax-free. Employer match dollars always go into the pre-tax bucket.