Compound Interest Calculator
See the power of compounding — watch your initial investment grow into wealth over time.
How It Works
Compound interest grows your money faster than simple interest because you earn returns on your returns. Even small amounts invested early can grow dramatically.
A = P(1 + r/n)^(n×t)
A = final amount · P = principal · r = rate · n = compounds/yr · t = years
Rule of 72
Divide 72 by the interest rate to find approximately how many years it takes to double your money. At 7%, money doubles every ~10 years.
Frequently Asked Questions
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. This "interest on interest" effect causes investments to grow exponentially over time.
A = P(1 + r/n)^(nt), where A is the final amount, P is principal, r is annual rate, n is compounds per year, and t is time in years.
Daily compounding yields slightly more than monthly, which yields more than annually. For most savings accounts and investments, monthly or daily compounding is standard.