Frequently Asked Questions
What is the Rule of 72?
The Rule of 72 is a simple formula to estimate the time needed for an investment to double: divide 72 by the annual interest rate to get the approximate years.
How accurate is the Rule of 72?
It is most accurate for interest rates between 6% and 10%. For very high or very low rates, the approximation becomes less precise.
Can it be applied to inflation?
Yes, you can estimate when prices will double. At 3% inflation, prices double in approximately 72/3 = 24 years.
Updated 2026 — latest rates