Compound Interest Calculator
See how investments grow over time
Formula
A = P(1 + r/n)^(nt)
- A = Final amount
- P = Principal (initial investment)
- r = Annual interest rate (decimal)
- n = Compounding periods per year
- t = Time in years
FAQ
What is the Rule of 72?
Divide 72 by your annual interest rate to estimate how many years to double your money. At 7%: 72 ÷ 7 ≈ 10.3 years.
What's the difference between APR and APY?
APR (Annual Percentage Rate) doesn't account for compounding. APY (Annual Percentage Yield) does — it reflects the actual annual return including compound interest.