Compound Interest Calculator
See how your investments grow with the power of compounding
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Frequently Asked Questions
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. This creates a snowball effect — your returns generate their own returns. Albert Einstein reportedly called it the "eighth wonder of the world." The formula is A = P(1 + r/n)^(nt), where P is principal, r is rate, n is compounding frequency, and t is time.
The Rule of 72 is a quick way to estimate how many years it takes to double your money. Divide 72 by the annual interest rate. For example, at 7% interest, your money doubles in approximately 72/7 ≈ 10.3 years. This is a useful mental math shortcut for financial planning.