Compound Interest
Compound growth from principal, rate, years and contributions.
Starting lump-sum investment amount
Expected annual return or bank deposit interest rate
Number of years to grow your investment (1–100)
Monthly (12 times / yr)
Additional amount invested at the end of each month
Final Balance
181,940
Total ROI: +81.9%
Total Principal 100,000
Total Interest +81,940
Total ROI +81.9%
FV = PV × (1 + r/n)ⁿᵗ
Yearly Growth Schedule 10 yrs
| Year | Total Invested | Total Interest | Balance | ROI |
|---|---|---|---|---|
| Start | 100,000 | 0 | 100,000 | 0.0% |
| Year 1 | 100,000 | +6,168 | 106,168 | +6.2% |
| Year 2 | 100,000 | +12,716 | 112,716 | +12.7% |
| Year 3 | 100,000 | +19,668 | 119,668 | +19.7% |
| Year 4 | 100,000 | +27,049 | 127,049 | +27.0% |
| Year 5 | 100,000 | +34,885 | 134,885 | +34.9% |
| Year 6 | 100,000 | +43,204 | 143,204 | +43.2% |
| Year 7 | 100,000 | +52,037 | 152,037 | +52.0% |
| Year 8 | 100,000 | +61,414 | 161,414 | +61.4% |
| Year 9 | 100,000 | +71,370 | 171,370 | +71.4% |
| Year 10 | 100,000 | +81,940 | 181,940 | +81.9% |
Rule of 72 (Doubling Time)
Divide 72 by the annual return rate to estimate doubling time in years
| Annual Rate | Doubling Time | Formula |
|---|---|---|
| 4% | 18.0 yrs | 72 ÷ 4 = 18 |
| 6% | 12.0 yrs | 72 ÷ 6 = 12 |
| 8% | 9.0 yrs | 72 ÷ 8 = 9 |
| 10% | 7.2 yrs | 72 ÷ 10 = 7.2 |
| 12% | 6.0 yrs | 72 ÷ 12 = 6 |
Compounding Formulas & Principles
- Future Value Formula (FV)：FV = PV × (1 + r/n)ⁿᵗ (PV: principal, r: annual rate, n: frequency, t: years)
- Compounding Frequency：Monthly Compounding: Interest is calculated monthly. Reinvesting gains each month compounds growth faster.
- Regular Contributions (DCA)：Regular Contributions: Adding a fixed amount monthly harnesses the compounding power of dollar-cost averaging.