Financial calculators
Compound Interest
Explore how time and regular contributions can affect an illustrative balance.
Inputs stay in your browser. Illustrations exclude taxes, fees, inflation, and market variability.
Illustrative future balance
Over 20 years
A constant-return illustration. Actual balances can rise or fall.
Methodology and assumptions
Contributions are added at the end of each month. For nominal annual rate r and compounding frequency n, the effective monthly rate is i = (1 + r/n)^(n/12) − 1. Each month: new balance = previous balance × (1 + i) + monthly contribution.
Equivalent future value over m months: P × (1 + i)^m + C × ((1 + i)^m − 1)/i. At zero return, future value equals P + C × m.
View the yearly results table
| Year | Contributions | Balance |
|---|---|---|
| 0 | $10,000 | $10,000 |
| 1 | $13,000 | $13,701 |
| 2 | $16,000 | $17,630 |
| 3 | $19,000 | $21,801 |
| 4 | $22,000 | $26,229 |
| 5 | $25,000 | $30,931 |
| 6 | $28,000 | $35,923 |
| 7 | $31,000 | $41,222 |
| 8 | $34,000 | $46,849 |
| 9 | $37,000 | $52,822 |
| 10 | $40,000 | $59,164 |
| 11 | $43,000 | $65,897 |
| 12 | $46,000 | $73,045 |
| 13 | $49,000 | $80,634 |
| 14 | $52,000 | $88,691 |
| 15 | $55,000 | $97,246 |
| 16 | $58,000 | $106,327 |
| 17 | $61,000 | $115,969 |
| 18 | $64,000 | $126,206 |
| 19 | $67,000 | $137,074 |
| 20 | $70,000 | $148,612 |
For general education only. These materials do not provide personalized investment, insurance, tax, or legal advice. Actual outcomes vary, and investments may lose value.