How to Use the 401(k) Calculator
- Enter your age, planned retirement age, current balance and salary.
- Enter your contribution percentage.
- Enter your employer’s match rate and the salary limit on the match.
- Set expected raises, investment return and inflation.
- Press Calculate and review the first-year figures.
Formula
Employee contribution = min(salary × % , IRS limit for age) Employer match = min(employee contribution, salary × match limit) × match rate Each month: balance = balance × (1 + return)^(1/12) + (employee + employer) ÷ 12 Salary grows by the raise rate each year.
Example Calculation
A 35-year-old earning $85,000 contributes 10% ($8,500). The employer matches 50% of contributions up to 6% of salary, adding $2,550. With 3% raises and a 7% return until age 65, the balance grows to about $1.86 million, or roughly $886,000 in today’s dollars at 2.5% inflation.
What Is a 401(k) Calculator?
A 401(k) calculator estimates how a workplace retirement account may grow given your contributions, your employer’s match and market returns. It is most helpful for deciding how much to contribute and whether you are on track.
How the Employer Match Works
Matches vary. A common formula is 50 cents per dollar on the first 6% of pay. Others match dollar for dollar up to 3%. Check your plan document; the match is effectively a guaranteed return on the contributions it applies to.
Factors That Affect Your Balance
- Contribution rate: the lever you control most directly.
- Time horizon: every additional year of growth adds substantially.
- Investment mix and fees: they drive net return.
- Raises: contributions based on a percentage rise with your salary.
Tips
- At minimum, contribute enough to capture the full match.
- Increase your rate by one point each year or with each raise.
- Review fund fees inside the plan.
- Do not cash out when changing jobs; roll the balance over.
Common Mistakes
- Leaving match money unclaimed.
- Ignoring vesting schedules on employer contributions.
- Investing too conservatively or too aggressively for your timeline without a plan.
Compare account types in 401(k) vs Roth IRA, and see the bigger picture with the retirement calculator.