Does the Rule of 72 actually work?

Asked by: Mr. Narciso Lakin DDS  |  Last update: January 16, 2026
Score: 5/5 (14 votes)

The rule of 72 is only an approximation that is accurate for a range of interest rate (from 6% to 10%). Outside that range the error will vary from 2.4% to 14.0%.

How accurate is the Rule of 72?

Just like with investment growth, divide 72 by the inflation rate (again, as a percentage) to estimate how many years it'll take for your money's buying power to get cut in half. The Rule of 72 is an estimate, and more accurate at around 8 percent interest.

What are the flaws of the Rule of 72?

However, the Rule of 72 is based on a few assumptions that may not always be accurate, such as a constant rate of return and compounding period. It also does not take into account taxes, inflation, and other factors that may impact investment returns.

How long will it take to double your money using the Rule of 72?

The rule is this: 72 divided by the interest rate number equals the number of years for the investment to double in size. For example, if the interest rate is 12%, you would divide 72 by 12 to get 6. This means that the investment will take about 6 years to double with a 12% fixed annual interest rate.

Do investments double every 7 years?

Key Takeaways

The Rule of 72 is a simple way to estimate how long it will take your investments to double by dividing 72 by your expected annual return rate. Higher-risk investments like stocks have historically doubled money faster (around seven years) compared with lower-risk options like bonds (around 12 years).

The Rule of 72: The Easiest Way to Double Your Money!

32 related questions found

How long will it take to double a $2000 investment at 10% interest?

However, the more precise method to calculate the exact number of years is using the exact doubling time which is 7.27 years, based on compound interest. Therefore, the correct answer to the question of how long it will take to double a $2,000 investement at 10% interest is A. 7.27 years.

Is 7% return on investment realistic?

A good return on investment is generally considered to be around 7% per year, based on the average historic return of the S&P 500 index, adjusted for inflation. The average return of the U.S. stock market is around 10% per year, adjusted for inflation, dating back to the late 1920s.

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%.

How can I double $5000 dollars in a year?

10+ Ways to Double $5,000
  1. Start a Side Hustle. Perhaps the most common method of making more money is starting a side hustle. ...
  2. Invest in Stocks and Bonds. ...
  3. Day Trade. ...
  4. Save More Money. ...
  5. Buy and Resell Items on Amazon and eBay. ...
  6. Build an eCommerce Business. ...
  7. Sell Your Stuff. ...
  8. Earn cashback When You Shop.

Is the Rule of 72 still valid?

The Rule of 72 applies to compounded interest rates and is reasonably accurate for interest rates that fall in the range of 6% and 10%. The Rule of 72 can be applied to anything that increases exponentially, such as GDP or inflation; it can also indicate the long-term effect of annual fees on an investment's growth.

What did Einstein say about the Rule of 72?

Einstein also said that “If people really understood the Rule of 72 they would never put their money in banks.” Suppose that a 10-year-old has $500 to invest. She puts it in her savings account that has a 1.75% annual interest rate.

What is the $1 rule?

Before buying an item, figure out how many times you'll use it. If it breaks down to $1 or less per use, I give myself the green light to buy it.

How to double 10k quickly?

15 Legit Ways How to Double $10k Quickly (Without Dangerous Get Rich Schemes)
  1. Retail Arbitrage.
  2. Swing Trade Stocks.
  3. Invest in High-Growth Stocks.
  4. Cryptocurrency Investing.
  5. Start an Airbnb Business.
  6. Lend on Peer-to-Peer Platforms.
  7. Invest in High-Yield Dividend Stocks.
  8. Fix and Flip Real Estate.

Is the Rule of 72 Risky?

Dividing 72 by the annual rate of return gives investors an estimate of how many years it will take for the initial investment to duplicate. It is a reasonably accurate estimate, especially at low interest rates.

How to double your money in 3 years?

To answer the question of how to double my money quickly, simply invest in a portfolio of investment options like ULIPs, mutual funds, stocks, real estate, corporate bonds, Gold ETFs, National Savings Certificate, and tax-free bonds, to name a few.

What is 1 doubled every day for 30 days?

If you start with 1 dollar and double it every day for 30 days, you would have approximately $1,073,741,824. This shows the concept of exponential growth. Like the penny example, this is not typically possible in real-world investing scenarios.

How to turn $5000 into $10000 quickly?

10 Clever Ways To Turn $5,000 Into $10,000
  1. Invest in an index fund. Rido/Adobe. ...
  2. Sell handmade crafts. Grigoriy/Adobe. ...
  3. Buy party supplies and rent them out. wavebreak3/Adobe. ...
  4. Get a certificate. Kateryna/Adobe. ...
  5. Max out an employee-matched retirement account. ...
  6. Flip furniture. ...
  7. Start a business at home. ...
  8. Resell discounted items.

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.

How to turn $100 dollars into $1,000 in a month?

10 best ways to turn $100 into $1,000
  1. Opening a high-yield savings account. ...
  2. Investing in stocks, bonds, crypto, and real estate. ...
  3. Online selling. ...
  4. Blogging or vlogging. ...
  5. Opening a Roth IRA. ...
  6. Freelancing and other side hustles. ...
  7. Affiliate marketing and promotion. ...
  8. Online teaching.

How long will it take $4000 to grow to $9000 if it is invested at 7% compounded monthly?

- At 7% compounded monthly, it will take approximately 11.6 years for $4,000 to grow to $9,000. - At 6% compounded quarterly, it will take approximately 13.6 years for $4,000 to grow to $9,000.

How long will it take $1000 to double at 5% interest?

To find out how many years it will take your investment to double, you can take 72 divided by your annual interest rate. For instance, if your savings account has an annual interest rate of 5%, you can divide 72 by 5 and assume it'll take roughly 14.4 years to double your investment.

How long will it take $10000 to reach $50000 if it earns 10% annual interest compounded semiannually?

Answer: 16.5 years Please show steps to solving this, using the below Equation.

What is Warren Buffett's annual return?

Their partnership in managing Berkshire produced arguably the most remarkable extended performance for investors ever recorded. Since they began operating Berkshire in 1965, the stock has risen at an annualized pace of 19.8%. The S&P 500 has had an annualized return of 10.2% during the same timeframe.

What is the safest investment with the highest return?

Here are some ways investors can take less risk but still generate a decent return:
  • High-yield savings accounts.
  • Money market funds.
  • Certificates of deposit (CDs).
  • Corporate bonds.
  • Treasurys.
  • Dividend stocks.
  • Preferred shares.

How much money do I need to invest to make $3,000 a month?

$3,000 X 12 months = $36,000 per year. $36,000 / 6% dividend yield = $600,000. On the other hand, if you're more risk-averse and prefer a portfolio yielding 2%, you'd need to invest $1.8 million to reach the $3,000 per month target: $3,000 X 12 months = $36,000 per year.