Compound interest: how to make time work for you
Understand why interest on interest makes such a difference over time — and try it right away.
With simple interest, you always earn on the initial amount. With compound interest, each month's earnings start earning too — the famous "interest on interest".
Why time matters so much
At first the difference is small. Over time, the share that comes from interest grows until it exceeds what you contributed. That's why starting early often matters more than contributing a lot.
Try it now
Test different contributions, rates and periods. The shortcuts use Selic and CDI rates updated daily.
Compound interest calculator
Final balance
R$125,302.74
- Total invested
- R$61,000.00
- R$1,000.00 upfront + 120 contributions of R$500.00
- Total interest
- R$64,302.74
- 51.32% of final balance
Equivalent monthly rate: 1.08%
Anyone who opens the link sees this same simulation. Nothing is stored.
Show year-by-year table
| Year | Total invested | Total interest | Final balance |
|---|---|---|---|
| 1 | 7,000 | 507 | 7,507 |
| 2 | 13,000 | 1,908 | 14,908 |
| 3 | 19,000 | 4,328 | 23,328 |
| 4 | 25,000 | 7,904 | 32,904 |
| 5 | 31,000 | 12,798 | 43,798 |
| 6 | 37,000 | 19,190 | 56,190 |
| 7 | 43,000 | 27,285 | 70,285 |
| 8 | 49,000 | 37,319 | 86,319 |
| 9 | 55,000 | 49,557 | 104,557 |
| 10 | 61,000 | 64,303 | 125,303 |
Contributions at the end of each month (the first one at the end of month 1). Yearly rate converted to the equivalent monthly rate. Taxes, fees and inflation are not considered: to compare investments after tax, use the fixed income calculator.
Things to keep in mind
- Past returns do not guarantee future returns.
- Taxes and fees reduce the final result.
- Always compare the rate with inflation over the period.