401(k) Calculator

401(k) Calculator

A 401(k) is the most powerful retirement savings tool most employees have access to, combining tax-deferred growth, automatic payroll deductions, and employer matching contributions that represent an instant return on your money. This calculator projects your balance at retirement by accounting for all three factors — your own contributions, your employer’s match, and compound investment growth over time. The difference between contributing 6% and 10% of a $75,000 salary starting at age 30 can exceed $400,000 by retirement, which makes understanding the math worth your time. Use these projections as a planning baseline, then adjust contribution rates to see what’s actually achievable on your current income.

How Your 401(k) Balance Is Calculated

Your projected balance applies the future value formula to recurring monthly contributions. Each month, your employee contribution plus your employer’s matching contribution is added to the account, and the full balance compounds at the expected annual return rate.

FV = PV(1 + r)^n + PMT x [((1 + r)^n - 1) / r]

Where PV is your current balance, PMT is the total monthly contribution (employee + employer match combined), r is the monthly rate of return (annual rate divided by 12), and n is the number of months until your target retirement age. The employer match is calculated first — typically a percentage of your contribution up to a salary cap — then added to your own contribution to get PMT.

Worked Examples

Sarah is 28 years old, earns $62,000, and contributes 5% of her salary ($3,100/year) to her 401(k). Her employer matches 50% on the first 6%, so she captures $1,550 in matching funds annually. Her current balance is $8,000. At 7% average annual return over 37 years to age 65, she projects a balance of roughly $780,000 — of which more than $530,000 comes from investment growth alone.

Marcus is 35 with a $95,000 salary. He contributes 10% ($9,500/year), and his employer matches 100% on the first 4% ($3,800/year). Starting from a $40,000 balance, he has 30 years of compounding ahead. At 7% annual return, his projected balance at 65 is approximately $1.48 million. If he had started at 30 instead of 35, that same setup would project to $2.1 million — a $620,000 difference from just five additional years.

Jennifer is 52 and contributing the maximum $23,500 per year (2025 limit) plus the $7,500 catch-up contribution, for a total of $31,000. Her employer adds $4,500. With a $210,000 existing balance and 13 years until retirement at 65, she projects roughly $870,000 at 7% return. Her catch-up contributions alone account for about $140,000 of that projected balance — a concrete illustration of why the IRS catch-up provision exists.

Scenarios at a Glance

When to Use This Calculator

• Before open enrollment — compare the projected impact of each available contribution rate so you choose deliberately instead of defaulting to whatever you set years ago
• After a raise — when your salary increases, model what happens if you direct half the raise toward your 401(k) rather than spending the full increase
• To evaluate job offers — a job paying $5,000 less but with a 100% match up to 6% may actually deliver more long-term compensation than a higher base with no match
• Catch-up planning after age 50 — run scenarios with and without the $7,500 catch-up contribution to quantify the retirement impact of maximizing your final working years
• Benchmarking against milestones — check whether your current balance and savings rate put you on pace for the 1x, 3x, 6x, 10x salary milestones by ages 30, 40, 50, and 67

Common Mistakes to Avoid

1. Not capturing the full employer match. If your employer matches 50% of your contribution up to 6% of salary, contributing only 4% means leaving 1% of your salary — $800 on a $80,000 income — on the table every year. Over 30 years at 7% return, that uncollected $800/year amounts to roughly $80,000 in lost retirement wealth.

2. Using a default contribution set years ago. Many people set a 3% contribution when they first enrolled and never changed it. At $70,000, 3% is $2,100/year. Bumping to 8% adds $3,500/year in contributions — an increase that, over 25 years at 7%, is worth roughly $230,000 extra at retirement.

3. Cashing out when changing jobs. Taking a $30,000 401(k) distribution at age 35 in the 22% bracket means paying $6,600 in taxes plus a $3,000 early withdrawal penalty — walking away with $20,400. Left invested for 30 more years at 7%, that $30,000 would have grown to about $228,000. The rollover to an IRA or new employer plan costs nothing and preserves the full amount.

4. Ignoring asset allocation. Sitting in a money market fund inside a 401(k) is not the same as investing for growth. At 5% instead of 7% annual return, a 30-year projection on a $60,000 salary with 6% contributions drops from $817,000 to about $560,000. Review your fund selections at least annually.

Current Context for 2026

The 2025 employee 401(k) contribution limit is $23,500, up from $23,000 in 2024. The catch-up contribution limit for ages 50-59 and 63-64 remains $7,500, and a new SECURE 2.0 provision allows workers aged 60-63 an enhanced catch-up of $11,250 starting in 2025, bringing their total limit to $34,750. The combined employee-plus-employer contribution cap is $70,000. Target-date funds remain the most common default investment inside 401(k) plans, typically holding a 90/10 stock-to-bond mix for workers 30+ years from retirement and gradually shifting more conservative. The long-run S&P 500 average is roughly 10% nominal or 7% after inflation — the 7% figure used in most retirement projections.

Tips

1. Contribute at least enough to capture your full employer match — it is an immediate 50-100% return on that portion of your savings before any market gains
2. Increase your contribution by 1% each year at annual review time; on a $70,000 salary the after-tax paycheck impact is roughly $45-55 less per month but the long-term compounding is substantial
3. If you are aged 50 or older, set your contribution to capture the full catch-up provision — $31,000 total in 2025 — even if it takes a couple of years to ramp up to that level
4. For Roth 401(k) decisions: if you are in the 12% or lower bracket, the Roth version usually wins because tax-free growth over decades outweighs the modest upfront savings from pre-tax contributions
5. Roll over old 401(k) accounts when you leave a job — consolidating into an IRA or your new employer’s plan keeps the money invested, simplifies tracking, and avoids the 10% penalty
6. Review your fund expense ratios. A fund charging 0.8% annually versus an index fund at 0.05% costs $750 more per year on a $100,000 balance — that gap compounds alongside your balance
7. Use this calculator once a year to reality-check your trajectory against your retirement income goal — if you need $1.5M and your current path projects $900K, you have time to adjust

Related Calculations

Understanding your 401(k) trajectory pairs naturally with a few other tools. The Compound Interest Calculator isolates the math of growth on a lump sum, useful for modeling a rollover or a bonus contribution. The IRA Calculator lets you compare whether maxing an IRA alongside your 401(k) fits your situation — the combined $7,000 IRA limit plus $23,500 401(k) limit gives high earners room to shelter $30,500 per year. The Roth IRA Calculator is the right tool once you have hit your 401(k) match threshold and are deciding where to put additional retirement dollars. Finally, the Retirement Calculator takes a top-down view — starting from your target monthly retirement income and working backward to the savings rate required to fund it.