How fast can you double your money? 6 cardinal rules of good investment - Thumb rules for your financial queries (2024)

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How fast can you double your money? 6 cardinal rules of good investment - Thumb rules for your financial queries? ›

For example, if you invest $10,000 at 10 percent compound interest, then the “Rule of 72” states that in 7.2 years you will have $20,000. You divide 72 by 10 percent to get the time it takes for your money to double. The “Rule of 72” is a rule of thumb that gives approximate results.

So, if the interest rate is 6%, you would divide 72 by 6 to get 12. This means that the investment will take about 12 years to double with a 6% fixed annual interest rate. This calculator flips the 72 rule and shows what interest rate you would need to double your investment in a set number of 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. 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.

Thumb Rule #1: Rule of 72

The Rule of 72 is a simple formula that helps you estimate the time it takes for your investment to double. To use this rule, divide 72 by the expected rate of return on your investment.

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.

The rule of 8-4-3 when it comes to compounding indicates a style of investment that accelerates growth with time. Initially, a corpus doubles within 8 years through an average annual return of 12% subsequently another doubling happens for the same period after another 4 years following its initial setting up.

Putting the seven percent rule into action is simple: Calculate seven percent of your gross annual income. For example, seven percent of $50,000 is $3,500. Divide this amount by 12 to get your monthly savings target.

The so-called Rule of 42 is one example of a philosophy that focuses on a large distribution of holdings, calling for a portfolio to include at least 42 choices while owning only a small amount of most of those choices.

What is the rule of thumb for doubling? ›

The Formula for the Rule of 72

The Rule of 72 can be leveraged in two different ways to determine an expected doubling period or required rate of return. To calculate the time period an investment will double, divide the integer 72 by the expected rate of return.

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.

The 1-1-1 Rule

Words of one syllable (1) ending in a single consonant (1) immediately preceded by a single vowel (1) double the consonant before a suffixal vowel (-ing, -ed) but not before a suffixal consonant (-tion).

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.

And for a 20-year investment, returns have been 100% positive. But given the possibility for short-term stock market volatility, you should only invest in an S&P 500 index fund if you don't expect that you'll need your money for around five years.

There are two approaches you could take. The first is increasing the amount you invest monthly. Bumping up your monthly contributions to $200 would put you over the $1 million mark. The other option would be to try to exceed a 7% annual return with your investments.

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 (1.10^7.3 = 2).

As a rate of return, long-term mutual funds can offer rates between 12% and 15% per year. With these mutual funds, it may take between 5 and 6 years to double your money.

For example, if an investment scheme promises an 8% annual compounded rate of return, it will take approximately nine years (72 / 8 = 9) to double the invested money. Note that a compound annual return of 8% is plugged into this equation as 8, and not 0.08, giving a result of nine years (and not 900).