The Rule of 72 | Primerica (2024)

FAQs

The Rule of 72 | Primerica? ›

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.

What Is the Rule of 72? 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.

It's worth noting, the “rule of 72” definition isn't necessarily perfectly accurate because past market results do not predict future market behavior. However, it's a “back of the napkin” way to determine where your portfolio might potentially be in the years ahead.

The number 72 is a better approximation for annual interest compounding at typical rates. For continuous compounding ln (2), which is about 69.3%, will give accurate results for any rate. Daily compounding is close enough to continuous compounding for most purposes, so 69.3 or 70 should be used.

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.

Final answer:

It will take approximately 15.27 years to increase the $2,200 investment to $10,000 at an annual interest rate of 6.5%.

Determining the allocation of assets is a pivotal choice for investors, and a widely used initial guideline by many advisors is the “100 minus age" rule. This principle recommends investing the result of subtracting your age from 100 in equities, with the remaining portion allocated to debt instruments.

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.

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 can I double 100k? ›

The classic approach of doubling your money involves investing in a diversified portfolio of stocks and bonds and is probably the one that applies to most investors. Investing to double your money can be done safely over several years but there's more of a risk of losing most or all of your money if you're impatient.

Penny Doubled For 30 Days Calculation and Chart

It is a tricky question, doubling a penny doesn't seem like it would amount to much right? Well at the end of 30 days that $0.01 is worth $5,368,709.12!

All you do is divide 72 by the fixed rate of return to get the number of years it will take for your initial investment to double. For example, if your investment earns 6% per year on average, you would take 72 divided by 6 to determine that it will take 12 years for your money to double.

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.

If you need to double your financial investment in 10 years, a savings account with a 5% interest rate, for instance, wouldn't help achieve your goals. You'd need something with a higher rate of return (at least 7.2%) to make that 10-year milestone happen.

One of those tools is known as the Rule 72. For example, let's say you have saved $50,000 and your 401(k) holdings historically has a rate of return of 8%. 72 divided by 8 equals 9 years until your investment is estimated to double to $100,000.