Investment Calculator
Project the future value of your investment portfolio including regular contributions. Get inflation-adjusted (real) returns, after-tax projections, the Rule of 72 doubling time, and a full year-by-year growth table with historical benchmark comparisons.
Investment Math & Concepts
Real (Inflation-Adjusted) Return
Real Rate ≈ Nominal Rate − Inflation Rate
Real FV = Nominal FV ÷ (1 + inflation)^years
Example: At 10% nominal return with 3% inflation, your real rate is ~6.8% (exact: (1.10/1.03) − 1). A $100,000 portfolio growing to $500,000 nominally may only represent $275,000 in today’s purchasing power.
After-Tax Return
After-Tax Gain = Total Gain × (1 − Tax Rate)
2025 US Long-Term Capital Gains Tax Rates:
| Filing Status | Income Threshold | LTCG Rate |
|---|---|---|
| Single | Up to $47,025 | 0% |
| Single | $47,026–$518,900 | 15% |
| Single | Over $518,900 | 20% |
| Married Filing Jointly | Up to $94,050 | 0% |
| Married Filing Jointly | $94,051–$583,750 | 15% |
| Married Filing Jointly | Over $583,750 | 20% |
Historical Asset Class Returns (USA, 1926–2024)
| Asset Class | Nominal Annual Return | Real Annual Return | Std Dev (Risk) |
|---|---|---|---|
| US Large Cap Stocks (S&P 500) | ~10.2% | ~7.0% | ~20% |
| US Small Cap Stocks | ~11.8% | ~8.5% | ~32% |
| International Developed | ~8.5% | ~5.5% | ~22% |
| Emerging Markets | ~9.5% | ~6.5% | ~30% |
| US Long-Term Gov. Bonds | ~5.4% | ~2.4% | ~11% |
| US Corporate Bonds (Inv. Grade) | ~5.8% | ~2.8% | ~9% |
| Real Estate (REITs) | ~9.6% | ~6.4% | ~18% |
| Gold | ~7.7% | ~4.5% | ~20% |
| US Treasury Bills (Cash) | ~3.3% | ~0.4% | ~3% |
| Inflation (CPI) | ~3.0% | — | — |
Source: Ibbotson/Morningstar SBBI Yearbook, CRSP data. Past performance not indicative of future results.
The $10,000 Investment at Different Rates — 30 Years
| Annual Rate | 10 Years | 20 Years | 30 Years | Multiple |
|---|---|---|---|---|
| 3% (savings/bonds) | $13,439 | $18,061 | $24,273 | 2.4× |
| 5% (balanced) | $16,289 | $26,533 | $43,219 | 4.3× |
| 7% (target date) | $19,672 | $38,697 | $76,123 | 7.6× |
| 10% (index fund) | $25,937 | $67,275 | $174,494 | 17.4× |
| 12% (aggressive) | $31,058 | $96,463 | $299,599 | 30.0× |
References
- Securities and Exchange Commission (SEC) — Introduction to Investing.
- IRS Publication 550 — Investment Income and Expenses; Schedule D instructions.
- Vanguard Research — Principles for Investing Success.
- Fama & French (2002) — The Equity Premium; historical return data.
- Morningstar / Ibbotson SBBI Yearbook — Asset class historical returns.
