The Rule of 72 | Primerica (2024)

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The Rule of 72 | Primerica? ›

Just take the number 72 and divide it by the interest rate you hope to earn. That number gives you the approximate number of years it will take for your investment to double. As you can see, a one-time contribution of $10,000 doubles six more times at 12 percent than at 3 percent.

The Rule of 72 is derived from a more complex calculation and is an approximation, and therefore it isn't perfectly accurate. The most accurate results from the Rule of 72 are based at the 8 percent interest rate, and the farther from 8 percent you go in either direction, the less precise the results will be.

The Rule of 72 is not precise, but is a quick way to get a useful ballpark figure. For investments without a fixed rate of return, you can instead divide 72 by the number of years you hope it will take to double your money. This will give you an estimate of the annual rate of return you'll need to achieve that goal.

The most basic example of the Rule of 72 is one we can do without a calculator: Given a 10% annual rate of return, how long will it take for your money to double? Take 72 and divide it by 10 and you get 7.2. This means, at a 10% fixed annual rate of return, your money doubles every 7 years.

Advantages and Disadvantages of Rule of 72

However, the Rule of 72 is based on a few assumptions that may not always be accurate, such as a constant rate of return and compounding period. It also does not take into account taxes, inflation, and other factors that may impact investment returns.

Do you know the Rule of 72? It's an easy way to calculate just how long it's going to take for your money to double. Just take the number 72 and divide it by the interest rate you hope to earn. That number gives you the approximate number of years it will take for your investment to double.

The magic number

The premise of the rule revolves around either dividing 72 by the interest rate your investment will receive, or inversely, dividing the number of years you would like to double your money in by 72 to give you the required rate of return.

To turn $5,000 into more money, explore various investment avenues like the stock market, real estate or a high-yield savings account for lower-risk growth. Investing in a small business or startup could also provide significant returns if the business is successful.

History. The Rule of 72 was first introduced in the late fifteenth century by the Franciscan friar and Italian mathematician Luca Pacioli.

How to get 11.5% on your money? ›

You can get more than 11 per cent from a new retail bond if you tie up your money for three years, but it doesn't come without risks.

The rule of 72 can help you forecast how long it will take for your investments to double. Divide 72 by the annual fixed interest rate to determine the rate at which the money would double. Historical returns on your investment type can help choose a realistic expected return rate, in some cases.

Though it was outlawed in 1992 for loans longer than 61 months, some lenders still use this practice. It's widely viewed as unfair to borrowers who may decide to pay off their loans early to save money on interest.

The Rule of 78 is an important consideration for borrowers who potentially intend to pay off their loans early. The Rule of 78 holds that the borrower must pay a greater portion of the interest rate in the earlier part of the loan cycle, which means the borrower will pay more than they would with a regular loan.

The Rule of 78s is also known as the sum of the digits. In fact, the 78 is a sum of the digits of the months in a year: 1 plus 2 plus 3 plus 4, etc., to 12, equals 78. Under the rule, each month in the contract is assigned a value which is exactly the reverse of its occurrence in the contract.

The value 72 is a convenient choice of numerator, since it has many small divisors: 1, 2, 3, 4, 6, 8, 9, and 12. It provides a good approximation for annual compounding, and for compounding at typical rates (from 6% to 10%); the approximations are less accurate at higher interest rates.

According to the rule of 72, you'll get 72 / 4 = 18 years. If you use the rule of 70, you'll get 70 / 4 = 17.5 years. Finally, if you do the original logarithm calculation, it'll actually take you about 17.501 years to double your money. So, the rule of 70 is a better estimate.

The rule of 72 can help you get a rough estimate of how long it will take you to double your money at a fixed annual interest rate. If you have an average rate of return and a current balance, you can project how long your investments will take to double.

What is the difference between Rule 72 and Rule 69? The main difference is that Rule of 72 considers simple compounding interest, whereas Rule of 69 considers continuous compounding interest. Additionally, the accuracy of Rule of 72 decreases with higher interest rates.