💹 Investment Calculator

Project long-term portfolio growth with initial investment, regular contributions, and expected annual return.

Investment Details

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Final Portfolio Value
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Total Invested
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Total Returns
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Inflation-Adjusted Value
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After-Tax Value
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Effective Annual Yield
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Return Multiple
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How Investment Growth Works

Long-term wealth building relies on three factors: principal (starting amount), consistent contributions, and compound returns. Time is the most powerful variable — starting early dramatically amplifies results.

FV = P(1+r)^n + PMT × [(1+r)^n − 1] / r
Where P = principal, r = monthly rate, n = months, PMT = monthly contribution

Historical Market Returns (US)

  • S&P 500 (1928–2024): ~10% average annual return; ~7% inflation-adjusted
  • Bonds (10-year Treasury): ~3–5% average annual return
  • 60/40 Portfolio: ~7–8% average annual return
  • Real Estate (REITs): ~8–12% average annual total return

The Rule of 72

Divide 72 by your annual return rate to estimate how many years it takes to double your money. At 8%, your investment doubles every 9 years (72 ÷ 8 = 9).

Should I invest in a taxable or tax-advantaged account? +
Max out tax-advantaged accounts first (401k up to $23,000, IRA up to $7,000 in 2024). These allow your investments to compound without annual tax drag. Traditional accounts defer taxes to withdrawal; Roth accounts grow tax-free. Use taxable brokerage accounts for savings beyond these limits.
What is dollar-cost averaging? +
Dollar-cost averaging (DCA) means investing a fixed amount at regular intervals regardless of market conditions. This reduces the risk of investing a lump sum at a market peak. Regular monthly contributions (as modeled here) are a form of DCA and are one of the most effective long-term wealth-building strategies.