Rule of 72 Calculator
Quickly estimate the number of years required to double an investment given a fixed annual rate of interest using the Rule of 72.
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Applications
The Rule of 72 is widely used by investors and financial planners to estimate the effect of compound interest on their portfolios. It helps in quickly evaluating investment returns, setting retirement goals, and understanding the impact of inflation over time.
The Formula
Divide the number 72 by your annual interest rate. For example, at an 8% annual return, your money will double in 72 / 8 = 9 years. It's a highly accurate approximation for rates between 6% and 10%.
Fun Fact: The earliest known reference to the Rule of 72 is found in Luca Pacioli's 1494 book 'Summa de arithmetica', which makes it over 500 years old!
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