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
Key Takeaways
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.
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.]
How can I double my money continuously? ›
The time-tested way to double your money over a reasonable amount of time is to invest in a solid, balanced portfolio that's diversified between blue-chip stocks and investment-grade bonds.
What will 50k be worth in 20 years? ›
Assuming an annual return rate of 7%, investing $50,000 for 20 years can lead to a substantial increase in wealth. If you invest the money in a diversified portfolio of stocks, bonds, and other securities, you could potentially earn a return of $159,411.11 after 20 years.
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.
How much money 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.
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 long will it take to increase a $2200 investment to $10,000 if the interest rate is 6.5 percent? ›
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%.
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.
1 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).
How to turn 100k into 1 million? ›
If you keep saving, you can get there even faster. If you invest just $500 per month into the fund on top of the initial $100,000, you'll get there in less than 20 years on average. Adding $1,000 per month will get you to $1 million within 17 years. There are a lot of great S&P 500 index funds.
How to double $1,000 quickly? ›
Here's how to invest $1,000 and start growing your money today.
- Buy an S&P 500 index fund. ...
- Buy partial shares in 5 stocks. ...
- Put it in an IRA. ...
- Get a match in your 401(k) ...
- Have a robo-advisor invest for you. ...
- Pay down your credit card or other loan. ...
- Go super safe with a high-yield savings account. ...
- Build up a passive business.
For a quick return on a $5,000 investment, consider options like stock trading, especially in high-growth sectors or investing in a diversified mutual fund. Short-term P2P lending can also be a way to see quicker returns, though it carries higher risk.
How many years does it take for my 401k to double? ›
With a 6% return, it would take 12 years (72/6), while with an 8% return it would take 9 years (72/8). So as you can see, even a small increase in average annual return may reduce the number of years it would take for an investment to double.
How often is your 401k supposed to double? ›
What Is the Rule of 72?
| Annual Rate of Return | Years to Double |
|---|
| 1% | 72 |
| 2% | 36 |
| 3% | 24 |
| 4% | 18 |
6 more rows"The longer you can stay invested in something, the more opportunity you have for that investment to appreciate," he said. Assuming a 7 percent average annual return, it will take a little more than 10 years for a $60,000 401(k) balance to compound so it doubles in size. Learn the basics of how compound interest works.
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.
