Retirement Planning Tool

Retirement & 401k Compound Interest Calculator

Calculate your exact employer match, project your compound interest over decades, and see your safe monthly withdrawal amount using the 4% rule.

Your Details

Current Age

Retirement Age

Current Savings ($)

Annual Salary ($)

Monthly Contribution ($)

Employer Match (%)

Match Up To (%)

Annual Return (%)

Inflation Rate (%)

Projected Retirement Balance

Monthly Income (4% Rule)

Total Free Money (Match)

Growth Over Time

Contribution Breakdown

Total Your Contributions

Total Employer Match

Total Compound Growth

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Understanding Your 401(k) Employer Match

An employer 401(k) match is one of the most powerful wealth-building tools available to employees. When your company matches your contributions, they're essentially giving you a guaranteed return on your investment — often 50% to 100% instantly.

For example, if you earn $75,000 and contribute 6% ($4,500/year), and your employer matches 50% up to 6%, they'll add $2,250 to your account annually. Over 35 years at 7% returns, that "free money" alone grows to over $320,000. Not contributing enough to get the full match is like leaving part of your salary on the table.

The 4% Rule: How Much Can You Withdraw?

The 4% rule, first published by financial advisor William Bengen in 1994, suggests that retirees can withdraw 4% of their portfolio in the first year of retirement and adjust that amount for inflation each subsequent year — with a very high probability the money will last at least 30 years.

This rule is based on historical market data using a balanced portfolio of 50% stocks and 50% bonds. While market conditions change, it remains the gold standard for retirement withdrawal planning. Our calculator uses this rule to estimate your safe monthly retirement income based on your projected savings.

The Power of Compound Interest in Retirement

Albert Einstein reportedly called compound interest "the eighth wonder of the world." In retirement planning, it's the engine that transforms modest monthly contributions into six- or seven-figure portfolios. Compound interest works by reinvesting your earnings, so those earnings generate their own earnings — creating an accelerating growth curve.

Time is the most critical factor. Starting at age 25 instead of 35 with just $500/month can mean an extra $600,000+ at retirement. That's the exponential nature of compounding — the later years produce the most dramatic growth. Our chart above visualizes exactly how your money accelerates over time.

Frequently Asked Questions

An employer match is "free money" your company contributes based on your own contributions. For example, a 50% match up to 6% of salary means if you contribute 6% of $75,000 ($4,500/year), your employer adds 50% of that — $2,250/year. Always contribute at least enough to get the full match.

The 4% rule is a widely-used guideline suggesting you can withdraw 4% of your retirement portfolio in the first year of retirement, then adjust for inflation each year after, with a high probability your money will last 30+ years. Monthly income = Total Balance × 0.04 ÷ 12.

Compound interest means your investment earnings generate their own earnings over time. A 25-year-old contributing $500/month at 7% annual return could have over $1 million by age 65 — with more than half coming from compound growth alone. The earlier you start, the more powerful the effect.

A conservative estimate is 6–7% for a balanced stock/bond portfolio. The S&P 500 has historically averaged about 10% annually before inflation, or roughly 7% after adjusting for ~3% inflation. Using 7% is a reasonable middle-ground for long-term planning.

Absolutely. Inflation erodes purchasing power over decades. At 2.5% annual inflation, $1 million in 35 years will feel like only about $420,000 in today's dollars. Our calculator adjusts your final balance for inflation so you see the real purchasing power of your retirement savings.

At minimum, contribute enough to get your full employer match — that's an instant 50–100% return. The 2024 IRS limit is $23,000/year ($1,917/month), or $30,500 if you're 50+. Financial advisors often recommend saving 15% of gross income for retirement.