Chuck Sears The Rule of 73 is a shortcut used to estimate how long it will take for an investment to double. Based on a fixed annual rate of return, it is similar to the Rule of 72.
I rarely use the Rule of 73 in favor of the Rule of 72; the following is an example of its usage.
if an investment grows at 7% per year, the estimated time for it to double would be:
73/7 = 10.43 years
Rule of 73 is useful for estimating compound interest growth. It also provides a more accurate estimate for certain interest rates compared to the Rule of 72.
The Rule of 72 dates back to at least the 15th century, when mathematicians like Luca Pacioli discussed it in early financial writings.
