Rule of 72

🧭 Background & Context The Rule of 72 is a quick formula that indicates how many years it takes for an investment to double at a fixed interest rate, by dividing 72 by the interest rate. It is an approximation based on compound interest calculations and works remarkably well for interest rates between roughly 5 and 15 percent. However, at very low or very high interest rates, the result deviates noticeably from the exact logarithmic calculation, highlighting its limitations. Viewed calmly, the rule is less a mathematical tool and more a didactic aid for intuitively grasping the exponential effect of compound interest. It sharpens awareness of how strongly time and interest rates influence asset growth, without needing a calculator. In financial education, it therefore serves as a quick mental shortcut, not as a precise forecasting instrument. Its practical value lies primarily in providing rough guidance for long-term savings or investment decisions, for example, to illustrate the impact of a single percentage point difference. Those who understand the rule quickly recognize that a higher return drastically shortens the doubling time, while inflation or fees can just as quickly negate this effect. 📊 Market Environment & Drivers The main drivers are structural in nature: demographics, technology, and institutional adaptability. Demographic change shifts demand from growth toward distribution, while digita …