Compound Interest Calculator
Calculate compound interest and final amount for any principal, rate, term, and compounding frequency, instantly in your browser.
How to use the Compound Interest Calculator
- Enter the principal: the amount you invest or deposit at the start.
- Enter the annual interest rate as a percentage.
- Enter the time period in years.
- Choose how often interest is compounded: annually, semi-annually, quarterly, monthly or daily.
- Click Run to see the final amount and the total interest earned.
How the Compound Interest Calculator works
With compound interest, the interest earned in each period is added to the balance, so the next period earns interest on the interest as well as on the original principal. The calculator uses the standard 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. Total interest is A − P. More frequent compounding produces a slightly higher result for the same nominal rate, which is why banks quote an annual percentage yield (APY) alongside the rate.
Frequently asked questions
- Is this compound interest calculator free?
- Yes. Calculate compound interest at no cost, with no account required.
- What is the compound interest formula?
- A = P(1 + r/n)^(n*t), where P is principal, r is annual rate, n is compounding frequency, and t is time in years.
- How does compounding frequency affect the result?
- More frequent compounding (e.g. daily vs annually) yields a slightly higher final amount for the same nominal rate.