Compound Interest Calculator
Compound interest calculator with monthly contributions: see your final balance, total contributions, interest earned and growth year by year.
A = P (1 + rn)n·t
How to use this calculator
- Type your input in the box.
- The result updates as you type.
- Use “Copy result” or “Copy link” to share it.
Compound interest earns interest on previous interest, so savings grow faster the longer they stay invested. Enter a starting amount, a monthly contribution, the expected annual return and the number of years.
Choose how often interest is compounded. The year-by-year table and bars show how much of the balance is your money and how much is growth.
Results are estimates for information only and do not constitute financial advice. Your lender’s or bank’s figures may differ.
Worked example
$10,000 invested at 5 % compounded annually grows to $16,288.95 in 10 years. Adding $100 a month with monthly compounding brings the total to about $32,000.
Frequently asked questions
What is the compound interest formula?
A = P(1 + r/n)ⁿᵗ, where P is the initial amount, r the annual rate, n the compounding periods per year and t the years. Regular contributions add the future value of an annuity.
What is the rule of 72?
Divide 72 by the annual rate in percent to estimate how many years money takes to double: at 8 %, about 9 years.