72sääntö

The 72sääntö, or Rule of 72, is a simplified mathematical formula used to estimate the number of years it takes for an investment to double at a fixed annual rate of interest. The rule states that you divide 72 by the annual interest rate to find the approximate number of years for the investment to double. For example, if an investment earns an annual interest rate of 8%, it would take approximately 9 years (72 / 8 = 9) to double.

Conversely, if an investor wants their money to double in a specific timeframe, say 10 years, they can divide 72 by the number of years to find the required interest rate. In this case, the required interest rate would be approximately 7.2% (72 / 10 = 7.2). The Rule of 72 is a handy mental shortcut for quickly assessing investment growth potential without complex calculations.

It's important to note that the Rule of 72 is an approximation. The accuracy of the rule decreases as the interest rate deviates significantly from typical rates. For lower interest rates, the rule tends to slightly underestimate the doubling time, while for higher rates, it can slightly overestimate. Despite its simplification, it remains a widely used tool for financial planning and understanding compound interest.