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.
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.
How can I legally double my money? ›
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 $2000 dollars in 24 hours? ›
How To Double Money In 24 Hours – 10+ Top Ideas
- Flip Stuff For Profit.
- Start A Retail Arbitrage Business.
- Invest In Real Estate.
- Play Games For Money.
- Invest In Dividend Stocks & ETFs.
- Use Crypto Interest Accounts.
- Start A Side Hustle.
- Invest In Your 401(k)
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 much was $10,000 invested in the S&P 500 in 2000? ›
Think About This: $10,000 invested in the S&P 500 at the beginning of 2000 would have grown to $32,527 over 20 years — an average return of 6.07% per year.
What is the 7 year rule in investing? ›
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%. 1 At 10%, you could double your initial investment every seven years (72 divided by 10).
Is 10% return on investment realistic? ›
Usually the implication is that they can expect, over a long time, a 10% return. Fortunately some ask, with some doubt, "Is a 10% return really reasonable?" It is not. While the average growth or return in the market (e.g., the S&P 500) is about 10%*, investors over time do not see that.
How to Turn a $200,000 Investment Into $1 Million
- Evaluate Your Starting Point. Putting together $200,000 to invest is no small feat. ...
- Estimate Your Risk Tolerance. Your risk tolerance will determine what investments you're comfortable making. ...
- Calculate Necessary Returns. ...
- Allocate Investments Wisely. ...
- Minimize Taxes and Fees.
How can you make $5,000 turn into $10,000? Turning $5,000 into $10,000 involves investing in avenues with the potential for high returns, such as stocks, ETFs or real estate. Another approach is to use the money as seed capital for a profitable small business or side hustle.
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 many years does a sum of money doubles itself in 7 years? ›
CONCEPT: Simple interest concept. Now, we want the money to be quadruple i.e. 4 times. ∴ The money will quadruple itself in 21 years.
How soon can you double your money? ›
Very few investors know how long it takes to double their money. Rule of 72 can be of help. Divide 72 by the expected rate of return and the answer is the number of years required to double your money. For example, if a bond offers 6 percent rate of interest per year, then you will double your money in 12 years.
Will my money double in 5 years? ›
Alternatively you can calculate what interest rate you need to double your investment within a certain time period. For example if you wanted to double an investment in 5 years, divide 72 by 5 to learn that you'll need to earn 14.4% interest annually on your investment for 5 years: 14.4 × 5 = 72.
How many years does it take to double a $100 investment when interest rates are 7 percent per year? ›
It will take a bit over 10 years to double your money at 7% APR. So 72 / 7 = 10.29 years to double the investment.
