What this calculator does
Compound interest is calculated on the initial principal and on interest accumulated from earlier periods. This calculator helps illustrate how a balance may grow under a constant assumed rate.
Try the Compound Interest Calculator
Enter your own figures and explore an estimate in the InvestCalc calculator.
Open calculator ↗Why compounding matters
When interest remains invested, later periods can generate returns on both the original principal and previously accumulated interest. The effect depends on the rate, frequency and duration.
Formula
Future value = Principal × (1 + annual rate ÷ compounding periods) raised to (compounding periods × years).
Compounding frequency
The frequency describes how often interest is added to the balance. Select the option that best reflects the account or product you are modelling.
Real-world considerations
Actual savings and investment products may apply variable rates, fees, taxes, withdrawal rules or different day-count conventions. Market returns are not guaranteed.
Frequently asked questions
Does compounding guarantee growth?
No. The formula illustrates growth at a constant positive rate. Real rates and investment returns may change.
Can I compare monthly and annual compounding?
Yes. Change the compounding frequency and compare the resulting estimates using the same principal, rate and period.