Compound Interest Calculator
Calculate compound interest growth over time.
How to Do It Manually
Compound interest grows on both the principal and accumulated interest. The more frequently it compounds, the more you earn (or owe).
A = P(1 + r/n)^(nt) where A = final amount, P = principal, r = annual rate (decimal), n = compounding periods/year, t = years
- Convert annual rate to decimal (divide by 100).
- Divide by compounding frequency n (e.g. monthly = 12).
- Add 1 and raise to the power of (n × t).
- Multiply by the principal P.
Frequently Asked Questions
What does 'compounding frequency' mean?
How often interest is calculated and added: annually (n=1), quarterly (n=4), monthly (n=12), daily (n=365).
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 6%, it doubles in about 12 years.