How To Use the Rule of 72 To Estimate Returns. Let's say you have an investment balance of $100,000, and you want to know how long it will take to get it to $200,000 without adding any more funds. With an estimated annual return of 7%, you'd divide 72 by 7 to see that your investment will double every 10.29 years.
How the Rule of 72 Works. For example, the Rule of 72 states that $1 invested at an annual fixed interest rate of 10% would take 7.2 years ((72/10) = 7.2) to grow to $2. In reality, a 10% investment will take 7.3 years to double ((1.107.3 = 2).
A borrower who pays 12% interest on their credit card (or any other form of loan that is charging compound interest) will double the amount they owe in six years.
Assuming long-term market returns stay more or less the same, the Rule of 72 tells us that you should be able to double your money every 7.2 years. So, after 7.2 years have passed, you'll have $200,000; after 14.4 years, $400,000; after 21.6 years, $800,000; and after 28.8 years, $1.6 million.
For example, with a 9% rate of return, the simple calculation returns a time to double of eight years.
If you earn 7%, your money will double in a little over 10 years. You can also use the Rule of 72 to plug in interest rates from credit card debt, a car loan, home mortgage, or student loan to figure out how many years it'll take your money to double for someone else.
Currently, money market funds pay between 4.47% and 4.87% in interest. With that, you can earn between $447 to $487 in interest on $10,000 each year. Certificates of deposit (CDs). CDs are offered by financial institutions for set periods of time.
The rule says that to find the number of years required to double your money at a given interest rate, you just divide the interest rate into 72. For example, if you want to know how long it will take to double your money at eight percent interest, divide 8 into 72 and get 9 years.
Using the rule, you take the number 72 and divide it by this expected rate. For example, if you have a $10,000 investment that has earned or that you anticipate will earn an average of 10% every year, it would take 72/10 = 7.2 years for your money to double.
The Bad news is that you wont be able to consistently double your money every day. The good news is that even if you have a penny to your name you can be a multimillionaire if you can double that penny 30 times over your lifetime.
Similarly, if you want to double your money in five years, your investments will need to grow at around 14.4% per year (72/5). If your goal is to double your invested sum in 10 years, you should invest in a manner to earn around 7% every year.
We started with $10,000 and ended up with $4,918 in interest after 10 years in an account with a 4% annual yield. But by depositing an additional $100 each month into your savings account, you'd end up with $29,648 after 10 years, when compounded daily. The interest would be $7,648 on total deposits of $22,000.
Bank Savings Accounts
As noted above, the average rate on savings accounts as of February 3rd 2021, is 0.05% APY. A million-dollar deposit with that APY would generate $500 of interest after one year ($1,000,000 X 0.0005 = $500).
With a retirement account of $300,000, this means an average return of about $15,000 per year.
A sum of $50,000 in cash can earn about $195 a year in an average bank savings account or as much as $2,300 if you put it into a high-quality corporate bond fund. Other options include money market accounts, money market funds, certificate of deposits and government and corporate bonds.
How much will $100k be worth in 20 years? If you invest $100,000 at an annual interest rate of 6%, at the end of 20 years, your initial investment will amount to a total of $320,714, putting your interest earned over the two decades at $220,714. What is an after-tax rate of return?
Present value of perpetuity:
So, a $100 at the end of each year forever is worth $1,000 in today's terms.
But over the long haul, you can expect your investments to grow at about 10% a year, doubling every seven years or so.
∴ The money will quadruple itself in 21 years.
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.