401(k) Calculator — 2026
A 401(k) is an employer-sponsored retirement savings plan that allows pre-tax (Traditional) or post-tax (Roth) contributions to grow tax-advantaged until retirement. In 2026, the IRS contribution limit is $23,500 (under 50) or $31,000 (age 50+). This calculator projects your balance at retirement using compound growth, models your employer match, and shows estimated monthly income using the industry-standard 4% withdrawal rule.
How 401(k) Growth Is Calculated
Your 401(k) grows through compound interest — your contributions earn returns, and those returns earn returns. The standard future value formula for regular contributions is:
| Variable | Definition |
|---|---|
| FV | Future Value — your projected 401(k) balance at retirement |
| PV | Present Value — your current 401(k) balance today |
| PMT | Monthly contribution (your contribution + employer match) ÷ 12 |
| r | Monthly return = Annual expected return ÷ 12 |
| n | Number of months until retirement |
Example: Starting with $25,000 at age 30, contributing $500/month (plus $150 employer match = $650/month total) at 7% annual return, you'll accumulate approximately $1.02M by age 65 — enough to generate $40,800/year ($3,400/month) using the 4% withdrawal rule.
💡 The Single Best 401(k) Move
Always contribute at least enough to capture your full employer match first. If your employer matches 50¢ for every $1 you contribute up to 6% of salary, that's an immediate 50% return on your investment before any market growth. Failing to capture this match is the equivalent of turning down a guaranteed 50% raise. After the match, the priority order is: Roth IRA ($7,000/year), then back to the 401(k) to hit the $23,500 limit. This sequence optimizes tax diversification across both pre-tax and post-tax retirement buckets.
401(k) Retirement Calculator — 2026
Your 401(k) Details
e.g., 50 = 50¢ per $1
e.g., 6 = matched up to 6%
Historical S&P 500 avg ≈ 10% nominal, ~7% inflation-adjusted
Retirement Projection
Projected Balance at Age 65
$1,848,568
Over 35 years
| Your Annual Contribution | $8,000 |
| Employer Annual Match | +$2,400 |
| Total Annual | $10,400 |
| Total Contributions | $389,000 |
| Investment Growth | +$1,459,568 |
Estimated Retirement Income (4% Rule)
Traditional vs. Roth (After-Tax Value)
Traditional
$1,441,883
After 22% tax at withdrawal
Saves $1,760/yr now
Roth
$1,441,883
100% tax-free at retirement
Growth Milestones
| Age 40 | $200,248 |
| Age 50 | $552,438 |
| Age 60 | $1,260,221 |
| Age 65 | $1,848,568 |
Based on your results — what to do next:
Does your 401(k) cover all of retirement?
Your 401(k) projects to $1,848,568 — but retirement income includes Social Security too. Model the full picture with the 4% rule.
Visualize ${fmt(r.balance)} compounding further
See what $1,848,568 grows to beyond retirement at 7% — and understand the exponential curve behind the number.
Add your 401(k) to your net worth
Your $1,848,568 401(k) balance is your largest asset. Track it alongside all your other assets and liabilities.