Investment Calculator

Project your investment growth over time with inflation adjustment. Compare nominal and real returns to understand your true purchasing power.

Investment Details

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Enter your investment details and click "Calculate" to project your growth.

Pro Tip

The real rate of return (after inflation) is what matters for planning your financial future. Always consider inflation when setting long-term financial goals.

Try the Inflation Calculator

Understanding Investment Growth

Investing is the process of putting money to work with the expectation that it will grow over time. The key principle behind long-term investing is compound growth, where your returns generate their own returns, creating an exponential growth curve.

The nominal return is the raw percentage your investment earns before accounting for inflation. The real return (inflation-adjusted) shows the actual increase in purchasing power. A 10% nominal return with 3% inflation gives roughly a 6.8% real return.

Dollar-cost averaging through regular monthly contributions reduces the impact of market volatility. By investing consistently, you buy more shares when prices are low and fewer when prices are high, potentially lowering your average cost per share.

Historical data shows that diversified stock portfolios have returned approximately 7-10% annually over long periods, though past performance does not guarantee future results. Time in the market generally outperforms attempts to time the market.

Investment Growth Formula

FV = P(1 + r/12)12t + PMT × [((1 + r/12)12t − 1) / (r/12)]

Where:

FV = Future value of the investment

P = Initial investment (present value)

r = Annual return rate (decimal)

t = Investment period in years

PMT = Monthly contribution

Example

$25,000 initial with $500/month at 8% for 20 years:

  • Initial investment grows to: ~$116,524
  • Monthly contributions grow to: ~$294,510
  • Total future value: ~$411,034 (nominal)
  • Total invested: $145,000
  • Inflation-adjusted value (at 3%): ~$227,415

Frequently Asked Questions

What is a reasonable expected return for a diversified portfolio?
Historically, the S&P 500 has returned about 10% annually before inflation (approximately 7% after inflation). A balanced portfolio of stocks and bonds may return 6-8% annually. Conservative estimates use 6-7% for planning purposes.
Why should I adjust for inflation?
Inflation erodes purchasing power over time. A million dollars in 20 years will not buy as much as it does today. Adjusting for inflation shows you the real value of your future wealth in today's purchasing power.
Is it better to invest a lump sum or dollar-cost average?
Statistically, lump-sum investing outperforms dollar-cost averaging about two-thirds of the time because markets tend to rise over time. However, DCA reduces risk of investing at a peak and may be psychologically easier for many investors.
How does investment period affect returns?
Time is the most powerful factor in investing. Due to compound growth, money invested for 30 years will grow significantly more than money invested for 20 years, even with the same contributions and return rate.