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
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).
Can I double my money in 7 years? ›
All you do is divide 72 by the fixed rate of return to get the number of years it will take for your initial investment to double. 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.
What is the rule of 7 doubling? ›
Divide 72 by your average expected annual return
If instead your average expected annual return was a more modest 7% (accounting for the typical annual inflation of around 3%), dividing 72 by 7 would result in 10.3, meaning it would take slightly over a decade for your money to double under those conditions.
What is the rule for money doubles every 7 years? ›
The Rule of 72 is not precise, but is a quick way to get a useful ballpark figure. For investments without a fixed rate of return, you can instead divide 72 by the number of years you hope it will take to double your money. This will give you an estimate of the annual rate of return you'll need to achieve that goal.
What is the 7 year rule in investing? ›
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.
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%.
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.
What is the 12 month rule for 401k? ›
In addition, if the employer cannot distribute the plan's assets as soon as administratively feasible—generally within 12 months of the termination date, then the plan is not considered terminated, and future compliance requirements should be met.
The 70% rule for retirement savings says your estimated retirement spending will be 70% of your pre-retirement, post-tax income. Multiplying your post-tax income by 70% can give you an idea of how much you may spend once you retire.
What is the doubling time trick? ›
In finance, the rule of 72, the rule of 70 and the rule of 69.3 are methods for estimating an investment's doubling time. The rule number (e.g., 72) is divided by the interest percentage per period (usually years) to obtain the approximate number of periods required for doubling.
What is the rule of 70 years? ›
The rule of 70 is used to determine the number of years it takes for a variable to double by dividing the number 70 by the variable's growth rate. The rule of 70 is generally used to determine how long it would take for an investment to double given the annual rate of return.
Does money really double every 7 years? ›
Examples of the Rule of 72
Given a 10% annual rate of return, how long will it take for your money to double? Take 72 and divide it by 10 and you get 7.2. This means, at a 10% fixed annual rate of return, your money doubles every 7 years.
How can I double 100k? ›
The classic approach of doubling your money involves investing in a diversified portfolio of stocks and bonds and is probably the one that applies to most investors. Investing to double your money can be done safely over several years but there's more of a risk of losing most or all of your money if you're impatient.
How to double 10,000 dollars? ›
Think about the type of strategy that works best for you, and then dive in!
- Flip Stuff For Money. ...
- Invest In Real Estate. ...
- Start An Online Business. ...
- Start A Side Hustle. ...
- Invest In Stocks & ETFs. ...
- Fixed-Income Investing. ...
- Alternative Assets. ...
- Invest In Debt.
The correct Answer is:21
Step by step video, text & image solution for A sum of money doubles itself in 7 years. In how many years it will become 4 times ? by Maths experts to help you in doubts & scoring excellent marks in Class 14 exams.
How long does it take to double your money with a 7% return? ›
Why it Pays to Know the Math
| Rate of Return | Rule of 72 # of Years to Double Money | Logarithmic Formula # of Years to Double Money |
|---|
| 5% | 14.4 | 14.2 |
| 6% | 12.0 | 11.9 |
| 7% | 10.3 | 10.2 |
| 8% | 9.0 | 9.0 |
15 more rowsSep 14, 2023
How long has it historically taken a stock investment to double? NYU business professor Aswath Damodaran has done the math. According to his math, since 1949 S&P 500 investments have doubled ten times, or an average of about seven years each time.
How many years can you double your money? ›
The Rule of 72 is a calculation that estimates the number of years it takes to double your money at a specified rate of return. If, for example, your account earns 4 percent, divide 72 by 4 to get the number of years it will take for your money to double. In this case, 18 years.
