The Rule of 72: A Simple Guide to Building Wealth

When it comes to investing, understanding the time it takes to double your money can be a game-changer. This is where the Rule of 72 comes in. Whether you’re a seasoned investor or just starting to dip your toes into the world of finance, the Rule of 72 is a powerful tool that can help you make more informed decisions about your investments. In this article, we will explain what the Rule of 72 is, how it works, and why it matters for your financial future.

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What is the Rule of 72?

The Rule of 72 is a quick and simple method to estimate the time it takes for an investment to double in value. By dividing the number 72 by the annual interest rate or expected rate of return, you can get an approximate number of years it will take for your investment to double.

Formula: Time to Double = 72 / Interest Rate

Rule of 72
Rule of 72. Source: Business Insider

For example, if you have an investment with an annual interest rate of 8%, you can use the Rule of 72 to estimate that it will take approximately 9 years for your investment to double (72 / 8 = 9).

See also: 15 Best Passive Income Ideas

How Does the Rule of 72 Work?

The Rule of 72 is based on the concept of compounding interest. When you invest your money, it has the potential to earn interest or grow over time. Compounding allows you to earn interest not only on your initial investment but also on the accumulated interest.

Let’s say you invest $10,000 in an account with a 6% annual interest rate. After the first year, your investment would grow to $10,600 ($10,000 + 6% interest). In the second year, you would earn interest not only on your initial $10,000 but also on the $600 interest earned in the first year. This compounding effect accelerates the growth of your investment.

The Rule of 72 helps you visualize this compounding process by giving you a rough estimate of how long it will take for your investment to double based on the interest rate.

Why Does the Rule of 72 Matter?

  1. Investment Planning: The Rule of 72 provides a valuable tool for planning your investments. By understanding how long it takes for your investment to double, you can set realistic financial goals and adjust your investment strategy accordingly.
  2. Comparing Investments: When evaluating different investment opportunities, the Rule of 72 allows you to compare the potential growth rates. By calculating the time it takes for each investment to double, you can make more informed decisions and choose investments that align with your goals.
  3. Time Value of Money: The Rule of 72 highlights the concept of the time value of money. It shows that the longer you invest, the more time your money has to grow through compounding. By starting early and allowing your investments to compound over time, you can potentially achieve significant wealth accumulation.


The Rule of 72 is a simple yet powerful tool for estimating the time it takes for your investments to double. By understanding this concept, you can make more informed decisions about your investment strategy, set realistic financial goals, and take advantage of the compounding effect to accelerate your wealth accumulation.

Remember, the Rule of 72 is a rough estimate and doesn’t account for factors like taxes, inflation, or market volatility. Nonetheless, it serves as an excellent starting point for evaluating investment opportunities and gaining a better understanding of the power of compounding.

So, whether you’re saving for retirement, planning for your child’s education, or simply aiming to grow your wealth, consider incorporating the Rule of 72 into your financial toolkit and unlock the potential for accelerated investment growth.

See also: 7 Best Assets to Own to Build Wealth

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