About the Compound Interest Calculator
Project the growth of savings or investments with compound interest. Add regular monthly contributions, choose how often interest compounds, and see the balance year by year.
Key features
- Future value with any compounding frequency
- Yearly, quarterly, monthly or daily compounding
- Regular monthly contributions
- Contributions vs interest breakdown chart
- Year-by-year growth table
- Multiple currencies
Watch your money grow
Compound interest is the engine behind long-term savings and investing. Enter a starting amount, a monthly contribution, an interest rate and a time period to see what your money could become, and how much of it is interest earned.
The compound interest formula
A = P × (1 + r/n)^(n × t)
- A: final amount
- P: principal (initial deposit)
- r: annual interest rate (decimal)
- n: compounding periods per year
- t: years
Monthly contributions are added as a series of deposits, each compounding from the month it's made.
The power of time
10,000 initial, 200 per month, 7% compounded monthly:
| Years | Contributed | Balance | Interest earned |
|---|---|---|---|
| 5 | 22,000 | 28,495 | 6,495 |
| 10 | 34,000 | 54,714 | 20,714 |
| 20 | 58,000 | 144,573 | 86,573 |
| 30 | 82,000 | 325,159 | 243,159 |
After 30 years, interest makes up three-quarters of the balance.
Doubling time (Rule of 72)
| Rate | Years to double |
|---|---|
| 3% | 24 |
| 6% | 12 |
| 8% | 9 |
| 10% | 7.2 |
| 12% | 6 |
Projections assume a constant rate and are for illustration, not financial advice. Real investment returns vary and can be negative.
Related calculators
Compare with the Simple Interest Calculator, plan monthly investing with the SIP Calculator, or set a target with the Savings Goal Calculator.
How to use the Compound Interest Calculator
- Enter your numbers in the fields above. Units and options can be changed at any time.
- The result updates instantly as you type; there's no calculate button to press.
- Check the breakdown under the main result for the details behind the number.
- Adjust the inputs to compare scenarios, for example a different rate or term.