Rule of 72

Type: Concept

As of November 2026, Rule of 72 has been mentioned in one podcast episode on The Ramsey Show (Nov 2026). Dave Ramsey recommended it: Dave explains and uses the Rule of 72 as a heuristic during investment growth examples.

In finance, the rule of 72, the rule of 70 and the rule of 69.3 are methods for estimating an investment's doubling time. The rule number is divided by the interest percentage per period to obtain the approximate number of periods required for doubling. Although scientific calculators and spreadsheet programs have functions to find the accurate doubling time, the rules are useful for mental calculations or when only a basic calculator is available.