Rule of 72
Divide 72 by your rate of return and you have the number of years it takes your money to double. Small rate changes, enormous end results.
It reveals both the power of compounding and the real cost of waiting to start.
Being financially responsible involves putting practical financial wisdom into action. Some of these clichés include curbing spending, paying off debt, and saving early and consistently. Compound interest can work in your favor, but it's important to understand that the effects of saving may not be as impressive as they once were.
The economic landscape has changed significantly over the past two decades. In the past, higher interest rates allowed individuals to grow their money through strategies like investing in certificates of deposit (CDs). However, interest rates have plummeted in recent years, and this trend is expected to continue according to the Federal Reserve. While saving is still important, it's necessary to explore alternative ways to grow your money and combat the impact of inflation in a low-interest-rate environment.
Check your expectations
There's no denying the reality that interest rates are currently low, which means your investments may not perform as well as they would have in the past, even with the power of compound interest. Additionally, combating the effects of inflation poses another challenge. However, as a young investor, you have the advantage of time.
Even with low-yield investment products, significant wealth can be generated over long periods, typically spanning decades. It's crucial to maintain realistic expectations when setting long-term savings goals. While retiring on your own island may be highly unlikely, with foresight and planning, your investments can still provide a comfortable retirement and peace of mind.
Simple interest
Example: 1% interest on the principal per year, starting from 100 in principal savings.
After 1 year: 101. After 2 years: 102. After 100 years: 100 becomes 200.
Compound interest
Example: 1% interest compounded annually, starting from 100 in principal savings.
After 1 year: 101. After 2 years: 102.01, because your 1 also earns 1% interest. After 3 years: 103.03 — the magic of compounding.
Experts have derived a simple formula to estimate the number of years your money doubles through compounding, called the “Rule of 72.” The rule states that 72 divided by the interest rate per year equates to the number of years your money will double.
72 ÷ interest rate = number of years for money to double. Using the values above, 72 ÷ 1% = 72 years. Therefore 100 becomes 200 after 72 years, compared with 100 years at simple interest.
Small rate changes, large results
Another interesting thing to note about the magic of compounding: small changes in the interest rate mean millions in the end result of your savings.
Example: 100,000 invested at 4%, 8% and 12% at age 29. Using the Rule of 72, the number of years your money will double is 18, 9 and 6 years respectively. At a retirement age of 65 the difference is dramatic.
Obviously, the bigger the interest, the bigger the result. But the not-so-obvious beauty of compounding is that the difference between 4% and 8% is two times, while the difference between 400K and 1.6M is four times. The difference between 4% and 12% is three times, but the difference between 400K and 6.4M is sixteen times.