Investment Calculator
Calculate the future value of investments with monthly contributions. See how much your portfolio grows based on expected annual returns over time.
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Portfolio Value
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Total Invested —
Investment Returns —
Return Multiple —
How to Use This Calculator
- Enter your Initial Investment — any lump sum you start with.
- Enter your Monthly Contribution — consistent contributions dramatically boost results.
- Set the Expected Annual Return — use 7–8% for a diversified portfolio.
- Set the Investment Period in years — longer periods dramatically increase returns.
- Review the Portfolio Value and the Return Multiple to see growth.
Formula
Future Portfolio Value:
FV = P(1 + r/12)^(12t) + PMT × [(1 + r/12)^(12t) − 1] / (r/12)
- P = Initial investment
- r = Annual return rate (decimal)
- t = Years invested
- PMT = Monthly contribution
Example
Example: $10,000 initial, $500/month, 8% annual return, 25 years.
- Total Invested: $10,000 + ($500 × 300) = $160,000
- Investment Returns: $393,960
- Portfolio Value: $553,960
- Return Multiple: 3.46×
Frequently Asked Questions
- The S&P 500 has historically averaged about 10% annually before inflation (about 7% after inflation). For a diversified portfolio, 6–8% is a conservative long-term estimate. Individual results vary.
- Dollar-cost averaging means investing a fixed amount regularly (like $500/month) regardless of market conditions. This reduces the impact of volatility — you buy more shares when prices are low and fewer when prices are high.
- Lump sum investing typically outperforms dollar-cost averaging about two-thirds of the time, since markets tend to rise over time. However, monthly contributions are more practical for most people and reduce timing risk.
- 401(k) and IRA accounts offer significant tax advantages. Traditional accounts reduce taxable income now; Roth accounts grow tax-free. Maxing out these accounts before taxable investing is generally advisable.
- Inflation erodes purchasing power. A 10% nominal return with 3% inflation yields a 7% real return. Always consider real (inflation-adjusted) returns when planning long-term financial goals.