Rule of 70 Vs. Rule of 72: Definition, How They Work, and Example (2024)

FAQs

What is the difference between rule of 70 and Rule of 72? ›

The Rule of 70 is a calculation that determines how many years it takes for an investment to double in value based on a constant rate of return. The Rule of 72 is a shortcut or rule of thumb used to estimate the number of years required to double your money at a given annual rate of return and vice versa.

The Rule of 70 Formula

Hence, the doubling time is simply 70 divided by the constant annual growth rate. For instance, consider a quantity that grows consistently at 5% annually. According to the Rule of 70, it will take 14 years (70/5) for the quantity to double.

The Rule of 72 is a calculation that estimates the number of years it takes to double your money at a specified rate of return. If, for example, your account earns 4 percent, divide 72 by 4 to get the number of years it will take for your money to double. In this case, 18 years.

The Rule of 72 is a simple way to determine how long an investment will take to double given a fixed annual rate of interest. Dividing 72 by the annual rate of return gives investors a rough estimate of how many years it will take for the initial investment to duplicate itself.

For example, if the growth rate for China is estimated as 10%, the Rule of 70 predicts it would take seven years, or 70/10, for China's real GDP to double.

The Rule of 72 applies to compounded interest rates and is reasonably accurate for interest rates that fall in the range of 6% and 10%. The Rule of 72 can be applied to anything that increases exponentially, such as GDP or inflation; it can also indicate the long-term effect of annual fees on an investment's growth.

Let's say you estimate it will take $40,000 to renovate your new home before you resell it. Subtract that $40,000 from the $154,000 figure and you are left with $114,000. That figure is the estimated maximum price you should spend on your new home, according to the 70% rule.

The rule of 70 offers a way to figure out the doubling time of an investment. In other words, it shows you how many years it will take for your initial deposit to double in size. You'll need to know the specific rate of return in order to use the rule of 70 or doubling time formula.

The Rule of 70 states that: the doubling time of a variable approximately equals 70 divided by the growth rate of the variable.

You can also apply the Rule of 72 to debt for a sobering look at the impact of carrying a credit card balance. Assume a credit card balance of $10,000 at an interest rate of 17%. If you don't pay down the balance, the debt will double to $20,000 in approximately 4 years and 3 months.

How long does it take to double your money at 5 interest? ›

It would take 14.4 years to double your money. Applying the rule of 72, the number of years to double your money is 72 divided by the annual interest rate in percentage. In this question, the annual percentage rate is 5%, thus the number of years to double your money is: 72 / 5 = 14.4.

Reason : The Rule of 72 is a formula to approximate the time it will take for a given amount of money to double at a given compound interest rate. The formula is 72 divided by the interest rate earned. In a little over seven years, $100 will double at a compound annual rate of 10 percent (72/10 = 7.2 years).

Rule of 70: Divide 70 by the annual rate of return to estimate the number of years it takes for your investment to double. Rule of 72: Divide 72 by the annual rate of return to estimate the number of years it takes for your investment to double.

The Rule of 72 is a convenient method to estimate the approximate time for invested capital to double in value. By merely taking the number 72 and dividing it by the rate of return (or interest rate) expected to be earned, the output is the approximate number of years for an investment to double.

Five years is too short a period to expect a doubling of your investment. To achieve this target, you would need to earn a yearly return of 15 per cent, which seems highly ambitious, even for an all-equity portfolio.

The 70% rule for retirement savings suggests that your estimated retirement spending should be about 70% of your pre-retirement, after-tax income. For example, if you take home $100,000 a year, your annual spending in retirement would be about $70,000, or just over $5,800 a month.

The reason why the rule of 70 is popular in finance is because it offers a simple way to manage complicated exponential growth. It breaks down growth formulas into a simple equation using the number 70 alongside the rate of return.

The Rule of 72 is a simple formula that is used to estimate the time it takes for an investment to double in value, based on a fixed annual rate of return. It is more commonly used to determine compound interest, but it can be used in real estate too.