The Rule of 72 is an easy way to calculate how long an investment will take to double in value given a fixed annual rate of interest. Dividing 72 by the annual rate of return gives investors an estimate of how many years it will take for the initial investment to duplicate.
The rule of 72 is only an approximation that is accurate for a range of interest rate (from 6% to 10%). Outside that range the error will vary from 2.4% to 14.0%.
The rule is this: 72 divided by the interest rate number equals the number of years for the investment to double in size. For example, if the interest rate is 12%, you would divide 72 by 12 to get 6. This means that the investment will take about 6 years to double with a 12% fixed annual interest rate.
5% Rate of Return: If you're anticipating an average return of 5% on an investment, you'd divide this return into 72. This means, at a 5% rate of return, your investment would roughly double in 14.4 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%.
As per this thumb rule, the first 8 years is a period where money grows steadily, the next 4 years is where it accelerates and the next 3 years is where the snowball effect takes place.
The theme of the rule is to save your first crore in 7 years, then slash the time to 3 years for the second crore and just 2 years for the third! Setting an initial target of Rs 1 crore is a strategic move for several reasons.
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.
Before buying an item, figure out how many times you'll use it. If it breaks down to $1 or less per use, I give myself the green light to buy it.
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.
Here are the best low-risk investments in 2025:
High-yield savings accounts. Money market funds. Short-term certificates of deposit. Cash management accounts.
What is the Rule of 72? Here's how it works: Divide 72 by your expected annual interest rate (as a percentage, not a decimal). The answer is roughly the number of years it will take for your money to double. For example, if your investment earns 4 percent a year, it would take about 72 / 4 = 18 years to double.
Try Flipping Things
Another way to double your $2,000 in 24 hours is by flipping items. This method involves buying items at a lower price and selling them for a profit. You can start by looking for items that are in high demand or have a high resale value. One popular option is to start a retail arbitrage business.
The Rule of 72 can be leveraged in two different ways to determine an expected doubling period or required rate of return. To calculate the time period an investment will double, divide the integer 72 by the expected rate of return. The formula relies on a single average rate over the life of the investment.
The idea is simple: you go on a date every 7 days, take a day trip or weekend getaway every 7 weeks, and plan a full vacation every 7 months. Now, I know life gets busy, and relationships can slip into routines – but that's exactly why this 7/7/7 rule is gold.
Three hours before you go to sleep, stop drinking alcohol. Two hours before you go to sleep, stop eating food. One hour before you go to sleep, stop drinking fluids.
For the foreseeable future, you won't find any banks that offer 7% APY on savings accounts. However, you can find some credit unions that pay 7% or more on checking accounts. Before opening an account, take a close look at the terms and conditions to determine whether you can earn the advertised rate.
A stocks and shares Isa is likely to be most suitable. That is unless you will turn 55 within 30 years, in which case a pension might be a better tax wrapper for you. If you're unsure about the time horizon, you could invest in both a pension and a stocks and shares Isa.
Compounding is the process where you earn interest on already accumulated interest. You can simply follow the 8-4-3 rule of compounding to grow your money. Let's understand it with an example.
A simple way to estimate the time it takes to double your money with compound interest is the Rule of 72. By dividing 72 by your annual interest rate, you get the approximate number of years needed to double your investment. With an 8% yield, it would take approximately nine years to double your money (72 / 8 = 9).