The Power of 72 calculator: A Simple Way to Grow

The Power of 72 calculator estimates how long it will take for an investment to double at a certain rate of return. It is computed by dividing 72 by the investment’s annual rate of return.

For example, how long will it take to grow a $10,000 investment to $20,000 at an annual return of 8%?

72 times 8 is 9 years. At 8% interest, the initial $10,000 investment will quadruple to $20,000 in around 9 years.

How Does the power of 72 calculator Work?

Because of the mathematical laws of exponential growth, the power of 72 calculator works. When money increases at a constant yearly rate, the time it takes to double may be calculated by dividing 72 by the growth rate.

As an example:

  • It takes 72/2 = 36 years to double at 2% growth.
  • It takes 72/10 = 7.2 years to double at 10% growth.
  • It takes 72/20 = 3.6 years to double at 20% growth.

As a result, the shorter the doubling time, the higher the rate of return. This doubling time is approximated by the power of 72 calculator.

Also Read : Top Stocks Under Rs 200 with High FII Holdings

When to Use the Power of 72 calculator ?

The power of 72 calculator is best suited for making basic estimates and approximations. It simplifies the calculation of compound growth.

It may be used to estimate things like:

  • How long will it take to double your investment money?
  • The time required for an amount to double at a particular inflation rate.
  • The time required for a population to double in size at a particular growth rate.

It’s often used in finance for retirement planning and investment forecasting. However, it may be used for any compound growth computation.

The Power of 72 calculator is simple to use, however it only offers an approximation. The accurate compound interest formula is preferable for more extensive, precise computations. The rule of 72, on the other hand, is a quick and convenient tool.

Examples of the Rule of 72?

Here are a some examples :

  • You make a $5,000 investment with a 6% yearly return. 72/6 = 12 years. It will take around 12 years for the $1,000 investment to quadruple to $10,000.
  • The annual rate of inflation is 3%. 72/3 = 24 years. Prices will almost double in 24 years if this trend continues.
  • The population is expanding at a rate of 2% every year. 72/2 = 36 years. At such pace of increase, the population will double in 36 years.
  • You want to know how long it will take to double your money if you invest in equities that yield 10% per year on average. 72/10 = 7.2 years.

Divide 72 by the compound growth rate to get a decent general estimate of the doubling time.

Know more : Rule of 72 basic concept

What are the limitations of the Rule of 72?

While simple to apply, the Rule of 72 has certain limitations:

  • It only works with set, consistent growth rates. It gets less accurate with fluctuating rates.
  • It does not take into consideration the consequences of compounding. The Rule of 72 actually underestimates the time required to double.
  • It just calculates the estimated doubling time; no further numbers are provided.
  • It presupposes earnings reinvestment.

While beneficial for rapid mental math, exact mathematical formulas are preferable for more extensive financial modelling. The Rule of 72 provides a decent ballpark estimate.


The Rule of 72 is a simple shortcut for calculating compound growth doubling times. You may calculate how many years it will take for an initial sum to double in size or value by dividing 72 by the yearly growth rate.

This rule is simple to use; however, it only yields estimates. Use the correct compound interest formulas for more accurate computations.

Still, the Rule of 72 is a useful mental tool for simplifying difficult math and swiftly projecting investment growth.

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