Compound Interest Calculator
About the Compound Interest Calculator
See how savings grow when interest is added back to the balance. Enter a starting amount, a regular contribution, an interest rate and a time period, and the calculator shows the final balance and how much of it is interest rather than your own deposits.
This tool works in your browser: the files and text you use are processed on your device and are not uploaded.
How to use it
- Enter your principal, annual interest rate, and number of years.
- Choose how often interest compounds.
- Read the interest earned and final balance.
Frequently asked questions
What is the compound interest formula?
A = P × (1 + r/n)^(n·t), where P is the principal, r the annual rate (as a decimal), n the number of compounding periods per year, and t the number of years. Interest earned is A − P.
How does compounding frequency affect returns?
More frequent compounding grows money slightly faster because interest is added — and starts earning — sooner. The jump from yearly to monthly is meaningful; from monthly to daily it is small.
What is the difference between simple and compound interest?
Simple interest is charged only on the original principal, so it grows linearly. Compound interest is charged on principal plus accumulated interest, so it grows exponentially and pulls ahead over time.
Does this account for inflation, taxes, or fees?
No — it projects nominal growth. To think in today’s money, subtract expected inflation from the rate, and remember interest may be taxable depending on the account and country.
This calculator is for informational and educational purposes only and does not constitute financial advice. Verify important figures with your bank, lender, or a qualified financial advisor.