Blog

Compound Interest Explained: The Secret to Growing Your Money

Written by Members Plus Credit Union | Sep 2, 2026, 1:20:49 PM

When it comes to growing your money, understanding compound interest and how it works can give you an insight into how to effectively increase your savings over time. With more knowledge and a savvy plan, this concept can be essential for long-term growth and can help shape your way for financial success.

Understanding How Compound Interest Works

Compound interest might be one of the most powerful tools for building long-term wealth. Unlike simple interest, which is earned only on your original deposit (principal), compound interest allows you to earn interest on both your principal and the interest your money has already earned. In other words, your savings have the opportunity to grow faster over time because your earnings continue earning additional earnings.

The key to making compound interest work for you is consistency and patience. The earlier you start saving and the longer you leave your money invested, the greater its growth potential. That's why compound interest is especially valuable for long-term goals like buying a home, saving for retirement, or building a college fund.

One simple way to estimate your money's growth is by using the Rule of 72. Divide 72 by your annual interest rate to estimate how long it may take your investment to double. For example, if your savings earn a 6% annual return, your money could double in approximately 12 years.

Simple Interest vs. Compound Interest

One of the biggest mistakes people make is underestimating the power of compound interest. While simple interest grows at a steady pace because it's calculated only on your original deposit, compound interest accelerates your savings by allowing your earnings to earn even more earnings. The longer your money stays invested, the greater the difference becomes.

Simple Interest: This is calculated only on the principal amount of the deposit.

Example: The interest paid on a $1,000 investment at 5% is $50 per year. In 10 years, this would equal $500 in earned interest for a total of $1,500.

Compound Interest: This is calculated on principal and also pays interest on previously earned interest.

Example: The interest paid on a $1,000 investment at a rate of 5% (and annual compounding) means after 10 years, you would have a total of $1628.89.

And the longer your investment remains, the compound interest grows at a faster rate, increasing your earnings.

Making Compound Interest Work for You

Start Saving Early

The key to building wealth is to start saving early. Even small contributions now will show significant growth over decades, as time is the most important factor when using compound interest to grow your wealth.

Save Consistently

Making regular contributions to your savings accounts is a big part of successful savings. Even small, deposits made on a regular basis will show significant gains due to the snowball effect of compound interest. Save what you can now and gradually increase your contributions when your budget allows.

Accounts That Help You Earn Compound Interest

If you’re looking to open an account that offers compound interest, MPCU offers the following accounts to take advantage of compound interest:

    • Savings Accounts: A Members Plus Savings Account is a great way to become a member of the credit union and also earn a competitive savings interest rate. A Savings Account can be opened with as little as $5 and entitles you to all the benefits and privileges of being a credit union member!
    • Money Market Accounts: Earn more interest on your money than a regular savings account with MPCU's money market account, the best way to invest your savings at a higher rate without additional risk.
    • Certificate of Deposit (CD): Grow your savings even faster with some of the best Certificate of Deposit in MA at Members Plus where you will find competitive rates, a variety of term options, and a safe, guaranteed, risk-free investment option.

We invite you to contact our team of finance professionals at Members Plus to see which accounts would work best for your unique situation.

When Compound Interest Works Against You

  • How Compound Interest Affects Loans
    • When you have debt, compound interest can affect you negatively. Accounts like credit cards can increase your debt because unpaid balances can grow significantly due to compounding, which is calculated daily.
  • Reduce the Cost of Borrowing
    • To reduce the interest charges of a loan with compounded interest, pay more than the minimum required payment each month and make payments on time, which will reduce your interest and ensure your credit remains in good standing for the best rates.
Start Building Your Financial Future with Members Plus Credit Union

Compound interest is one of the most powerful tools for building long term wealth, but its greatest advantage is time. Whether you're saving for a first home, retirement, your child's education, or another major milestone, starting early and contributing consistently can make a significant difference over the years. Even small deposits made regularly have the potential to grow into something much larger through the power of compounding.

As you continue your financial journey, MPCU is here to help. MPCU offers Money Management™, an easy to use financial management tool that keeps all your account information, even accounts at other financial institutions, at your fingertips, allowing you to track spending, create budgets, see your spending and saving habits, and more.