Compound interest calculator
Enter a starting amount, monthly contribution, annual rate and years to see the final balance, contributions and interest earned.
| Year | Contributed | Interest | Balance |
|---|---|---|---|
| 1 | 2,200.00 | 79.05 | 2,279.05 |
| 2 | 3,400.00 | 223.53 | 3,623.53 |
| 3 | 4,600.00 | 436.81 | 5,036.81 |
| 4 | 5,800.00 | 722.38 | 6,522.38 |
| 5 | 7,000.00 | 1,083.97 | 8,083.97 |
| 6 | 8,200.00 | 1,525.44 | 9,725.44 |
| 7 | 9,400.00 | 2,050.90 | 11,450.90 |
| 8 | 10,600.00 | 2,664.64 | 13,264.64 |
| 9 | 11,800.00 | 3,371.17 | 15,171.17 |
| 10 | 13,000.00 | 4,175.24 | 17,175.24 |
How to use it
Enter the starting amount, the contribution you add each month, the annual interest rate (in percent) and the number of years. Choose how often interest compounds (monthly, quarterly or yearly) and whether each contribution is made at the start or the end of the month. Below you get the final balance, total contributions, interest earned, a growth chart and a table by year.
The formula
Without contributions: final amount = starting amount × (1 + r / n)^(n × years), where r is the annual rate as a decimal (5% = 0.05) and n is the number of compounding periods per year. With monthly contributions the calculator steps through every month: the balance grows by the equivalent monthly rate (1 + r / n)^(n / 12) − 1 and then the contribution is added.
- The longer the period, the larger the share of the balance that comes from interest.
- More frequent compounding adds a little, but the rate and the time matter far more.
- A contribution made at the start of the month earns interest one month longer.
Good to know
This is a theoretical calculation with a constant rate: taxes, fees and inflation are not included, and real investment returns vary. Everything is calculated in your browser and nothing you enter is sent anywhere.