Retirement Calculator

What Does This Retirement Calculator Do?

This tool projects how much money you could accumulate by your target retirement age, given your current savings, monthly contributions, and an assumed average annual investment return. It uses the future value formula for compound interest — the same math that underpins every 401(k) projection illustration.

The goal is not a precise forecast — markets are unpredictable and life changes constantly. The goal is to give you a directional answer to the question everyone asks: "Am I on track?"

The Formula Behind the Numbers

The calculator computes two separate future values and adds them together:

Example: Starting at 30, Retiring at 65

That result assumes consistent contributions and a steady 7% return, which no investment guarantees. But it illustrates how powerful the combination of time and regular contributions is — a principle financial planners call "the compounding effect."

What Annual Return Should You Use?

This is the question that most retirement calculators dodge. Here are the figures most financial planners reference as long-term historical benchmarks:

• All-stock portfolio (e.g. S&P 500 index fund): ~7% real return (inflation-adjusted) historically
• Balanced portfolio (60% stocks / 40% bonds): ~5–6% real return
• Conservative portfolio (more bonds, cash): ~3–4% real return
• High-yield savings / CDs only: 4–5.5% nominal (varies, and not inflation-adjusted)

Using 6–7% for a long-term stock-heavy retirement account is a reasonable planning assumption. Run your numbers at both 5% and 8% to see the range.

The 4% Rule: How Much Do You Need to Retire?

Once you know your projected balance, a common planning benchmark is the 4% rule: you can sustainably withdraw 4% of your portfolio annually in retirement without depleting it over a 30-year period. Based on historical market returns, this rule has held up well.

To use it: divide your desired annual retirement income by 0.04. For example:

• Want $50,000/year → need at least $1,250,000 saved
• Want $80,000/year → need at least $2,000,000 saved

Compare that target to your projected balance from this calculator, then adjust your monthly contributions to close any gap.

Common Mistakes to Avoid

• Using an overly optimistic return rate — Assuming 10–12% for a multi-decade projection ignores real-world volatility and the fact that most diversified portfolios include bonds and cash, not just equities. A more conservative 6–7% avoids overstating your future balance.
• Treating the result as inflation-adjusted — This calculator projects nominal dollars. A projected $1 million in 35 years will not have the purchasing power of $1 million today. Either use a lower "real" return rate or mentally discount the result for inflation.
• Forgetting employer matching or other income sources — If your employer matches retirement contributions, that match should be added to your monthly contribution figure, or the projection will understate your actual trajectory.
• Assuming contributions stay flat over decades — Most people increase contributions as income grows. Entering today's contribution amount as a constant for 30+ years will likely underestimate your real ending balance.
• Skipping the "what if I stop working early" scenario — If you plan to retire early or take career breaks, re-run the calculator with a shorter contribution period rather than assuming contributions continue uninterrupted until retirement age.

Frequently Asked Questions