Whether you want to evaluate offers that promise to "double your money fast" or establish investment goals for your portfolio, a quick-and-dirty method will show you how long it will take to double your money. It's called the Rule of 72 and can be applied to any investment.
How the Rule Works
To use the Rule of 72, divide the number 72 by an investment's expected annual return. The result is the number of years it will take, roughly, to double your money. For example, if the expected annual return of a bank Certificate of Deposit (CD) is 2.35% and you have $1,000 to invest, it will take 72/2.35 or 30.64 years for you to double your original investment to $2,000. If the expected annual return on a CD is 5% and you invest the same amount, it will take you 14.4 years to double your money.
CDs are great for safety and liquidity, but let's look at stocks. It's impossible to know in advance what will happen to stock prices. We know that past performance does not guarantee future returns. But by examining historical data, we can make an educated guess. According to Standard and Poor's, the average annualized return of the S&P index, which later became the S&P 500, from 1926 to 2020 was 10%. At 10%, you could double your initial investment every seven years (72 divided by 10). In a less-risky investment such as bonds, which have averaged a return of about 5% to 6% over the same period, you could expect to double your money in about 12 years (72 divided by 6).
Keep in mind that we're talking about annualized returns or long-term averages. In any given year, stocks might return 25% or lose 30%. Over a long period, the returns will average out to 10%. The Rule of 72 doesn't mean that you'll be able to take your money out of the stock market in 10 years. You might have doubled your money by then, but the market could be down, and you might have to leave your money in for several more years until things turn around. If you must achieve a certain goal or be able to withdraw your money by a certain time, the Rule of 72 isn't enough. You'll have to plan carefully, choose your investments wisely, and keep an eye on your portfolio.
Achieving Your Investment Goals
A professional financial advisor may be your best bet for achieving specific investing goals, but the Rule of 72 can help you get started. If you know that you need to have a certain amount of money by a certain date, for example, for retirement or to pay for your newborn child's college tuition, the Rule of 72 can give you a general idea of which asset classes you'll need to invest in to achieve your goal.
First, you can use the Rule of 72 to determine how much college might cost in 18 years if tuition increases by an average of 4% per year. Divide 72 by 4% and you know that college costs are going to double every 18 years.
Right now you have $1,000 to invest and with an 18-year time horizon, you want to put it all in stocks. We saw in the previous section that investing in the S&P 500 has historically allowed investors to double their money about every six or seven years. Your initial $1,000 investment will grow to $2,000 by year 7, $4,000 by year 14, and $6,000 by year 18. Suddenly 18 years isn't as long a time horizon as you thought, perhaps leading you to rethink your investment strategy.
The Bottom Line
While the Rule of 72 is a good investment guideline, it only provides a framework. If you're looking for a more precise outcome, you'll need to better understand an asset's future value formula. The Rule of 72 also does not take into account the effect of investment fees, such as management fees and trading commissions, can have on your returns. Nor does it account for the losses you'll incur from any taxes you have to pay on your investment gains.
FAQs
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. Based on the above, you would need to earn 10% per year to double your money in a little over seven years.
Does a 401k double every 7 years? ›
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.
Does the S&P 500 double every 7 years? ›
According to his math, since 1949 S&P 500 investments have doubled ten times, or an average of about seven years each time. In some cases, like 1952 to 1955 or 1995 to 1998, the value of the investment doubled in only three years.
What is the 7 year rule for investing? ›
To estimate the number of years it would take to double your money at a 7% annual rate of return, you can use the Rule of 72. Divide 72 by the annual rate of return: 72 ÷ 7 = 10.29.
Is 7% annual return realistic? ›
In short, the average stock market return since the S&P 500's inception in 1926 through 2018 is approximately 10-11%. When adjusted for inflation, it's closer to about 7%. [Since we're talking citations in this post: Investopedia.]
What age should you have 100k in 401k? ›
“By the time you hit 33 years old, you should have $100,000 saved somewhere,” he said, urging viewers that they can accomplish this goal. “Save 20 percent of your paycheck and let the market grow at 5% to 7% per year,” O'Leary said in the video.
What is the 5 year rule for 401k? ›
Contributions and earnings in a Roth 401(k) can be withdrawn without paying taxes and penalties if you are at least 59½ and had your account for at least five years. Withdrawals can be made without penalty if you become disabled or by a beneficiary after your death.
How long does it take 100k to double? ›
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.
What is a good 10 year return on investment? ›
5-year, 10-year, 20-year and 30-year S&P 500 returns
| Period (start-of-year to end-of-2023) | Average annual S&P 500 return |
|---|
| 5 years (2019-2023) | 15.36% |
| 10 years (2014-2023) | 11.02% |
| 15 years (2009-2023) | 12.63% |
| 20 years (2004-2023) | 9.00% |
2 more rowsMay 3, 2024
You can get more than 11 per cent from a new retail bond if you tie up your money for three years, but it doesn't come without risks.
Now, you may be thinking that $1,000 a month for 20 years is a lot of money -- and you're right. But it's nowhere near $687,306.72. In fact, the actual value of your contributions alone would be $240,000, so you could end up with about $447,307 more than the amount you put in.
Should your money double every 7 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). The Rule of 72 is reasonably accurate for low rates of return.
What happens if you invest 20000 a month for 10 years? ›
If someone would have started investing Rs 20,000 monthly 10 years ago in this scheme, the value of their corpus would have been Rs 93.81 lakh in present times. The total investment during the entire period would have been Rs 24 lakh, while the wealth gain would have been Rs 69.81 lakh.
How much do I need to invest to make $1000 a month? ›
A stock portfolio focused on dividends can generate $1,000 per month or more in perpetual passive income, Mircea Iosif wrote on Medium. “For example, at a 4% dividend yield, you would need a portfolio worth $300,000.
Where can I get 12% returns? ›
Getting a 12% return on investment requires taking on higher risks, such as investing in equity mutual funds, individual stocks, or alternative assets such as real estate or peer-to-peer lending platforms. It's important to have a long-term investment horizon and diversify your portfolio to manage risks.
How much money do I need to invest to make $3,000 a month? ›
Imagine you wish to amass $3000 monthly from your investments, amounting to $36,000 annually. If you park your funds in a savings account offering a 2% annual interest rate, you'd need to inject roughly $1.8 million into the account.
How many years does it take for my 401k to double? ›
Your investments
With an annual 4% return, it would take 18 years (72/4) to approximately double. With a 6% return, it would take 12 years (72/6), while with an 8% return it would take 9 years (72/8).
How much does a 401k go up every year? ›
That being said, although each 401(k) plan is different, contributions accumulated within your plan, which are diversified among stock, bond, and cash investments, can provide an average annual return ranging from 3% to 8%, depending how you allocate your funds to each of those investment options.
How much does a 401k grow every year? ›
Many retirement planners suggest the typical 401(k) portfolio generates an average annual return of 5% to 8% based on market conditions. But your 401(k) return depends on different factors like your contributions, investment selection and fees. Sometimes broader trends can overwhelm these factors.
Do investments double in 7 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).
