401k Calculator

This calculator projects your 401k balance at retirement based on your contributions, employer match, and investment return assumption.

• Current Balance: your current 401k account value. Log in to your plan provider (Fidelity, Vanguard, etc.) to find this.
• Monthly Contribution: the amount deducted from your paycheck each month. For 2024, the IRS limit is $23,000 per year ($1,916/month), or $30,500 if you are 50 or older.
• Employer Match: a common match is 50% on up to 6% of salary. If your salary is $60,000, that means your employer contributes up to $1,800/year in free money.
• Expected Annual Return: the S&P 500 has averaged about 10% annually before inflation. A diversified portfolio of stocks and bonds averages around 7% after adjusting for inflation. Use 6-8% for a conservative estimate.
• Inflation-Adjusted Value: shows what your retirement balance will be worth in today's dollars, accounting for purchasing power lost to inflation.

Your 401k grows through three sources: your contributions, employer contributions, and investment gains. The growth formula compounds monthly:

Balance = Previous Balance × (1 + r/12) + Monthly Contributions

Where r is the annual return rate. Compounding monthly means your gains earn gains every month, not just once a year.

Employer match example: 50% match on up to 6% of salary. On a $60,000 salary, 6% = $3,600/year. Your employer adds 50% of that = $1,800/year = $150/month in free money. Always contribute at least enough to capture the full employer match.

4% rule: a widely cited guideline suggests withdrawing 4% of your balance in year one of retirement, then adjusting for inflation each year. On a $1 million balance, that is $40,000/year or $3,333/month.

Inflation adjustment: Inflation-Adjusted Value = Balance / (1 + inflation rate)^years. At 2.5% inflation over 35 years, $1 million at retirement buys what $420,000 buys today.