⚡ Free Online Tool
Compound Interest Calculator
Discover the power of compounding. Calculate how your money grows exponentially with optional monthly contributions over any time period.
❓ Frequently Asked Questions
What is compound interest? +
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Einstein reportedly called it the eighth wonder of the world.
Compound vs simple interest: which is better? +
Compound interest is always better for investments. For a $10,000 investment at 8% for 20 years: simple interest = $16,000 profit; compound interest = $36,610 profit.
How often should interest compound? +
More frequent compounding = higher returns. Daily compounding gives the most returns, but the difference vs monthly compounding is typically under 0.1% annually.
What is the Rule of 72? +
Divide 72 by the annual interest rate to estimate how many years it takes to double your money. At 8% interest: 72 ÷ 8 = 9 years to double.