The Big Difference Compound Interest Can Make to Small Savings

by Gary Foreman

The difference between financial success and failure can be quite small. What makes such a difference? It’s compound interest. We explore the impact it can have on your financial future.

Sometimes the difference between success and failure is very small. Occasionally you’ll see a race (NASCAR, horse or foot) that will be decided by just an inch or two. Such a tiny amount determines winners and losers.

What’s also striking is how much difference that can make in the future. Our stock car winner will take home a bigger prize purse. They’ll find it easier to get sponsors. Winning opens many doors.

A similar thing happens in personal finance. The difference between financial success and failure is really quite small. And, somewhat surprisingly, it’s not tied to being more disciplined or working harder your entire life. It’s a simple rule of economics that can work for or against us.

What is it that makes such a difference? It’s compound interest. It’s truly the double-edged sword of personal finance.

Compound Interest Can Work for You…

When it’s working for you, compound interest is a wonderful thing. If you save a dollar today and invest it (earning interest or profit), it will be worth more tomorrow and still more the day after that. If you wait long enough, even relatively small amounts can grow quite large.

…or Against You

When compound interest is working against you, when you borrow money, it can be costly if you aren’t careful. Sure, some loans you carry are considered “good” debt and they can help you increase your net worth and pay for things that will have long-term value, such as a home. However, too many of us take out loans or pay interest on credit cards to pay for depreciating assets that negatively impact our finances and financial futures. 

The Difference Between Saving and Borrowing: An Example

Let’s take a look at the difference between saving/investing $1000 and spending/borrowing the same amount of money.

Saving $1000 requires some effort on the front end. You’ll need to find a way to accumulate the money. After that, you’ll decide where to invest it. From that point on, it’s just a matter of monitoring your investment. No heavy lifting required.

That $1000 you saved, if invested today earning 9% (the long-term average for stocks), would be worth $2367 in 10 years, $5604 in 20 years, or $13,268 in 30 years. Again, that’s just from the initial investment. You don’t need to add anything to the account.

What happens if you end up on the other side of the coin? If you borrowed and spent $1000, you’ll be paying interest on the borrowed money. That requires you to work to earn the money over and over again. At 15% (a fairly typical rate on credit card accounts), you’ll need to come up with $150 just to cover the interest every year.

So borrowing that grand will cost you $1500 in interest payments in 10 years, $3000 in 20 years, or $4500 in 30 years.

Related: The Rule of 72 (or How To Easily Double Your Debt)

Get Started Making Compound Interest Work for You

What would happen if you made two decisions? One to not spend/borrow the $1000 and another to save $1000. How would that work out? Well, in 30 years, the difference in what you would have spent in interest payments and what you would have saved works out to over $16,700.

Now I can hear you say that $1000 is a lot of money. How could you manage to come up with that much?

OK, let’s mention just a few simple ways. Skipping a $4 latte every day would save $1460 in one year.

If you bring in your lunch three days a week, you’ll save about $5 per lunch or $1250 in one year. This way, saving a grand takes less than a year.

Most of us can find a place or two where we could save $10 to $15 a week. But, maybe you’ve already cut your spending down to essentials. There’s no place to cut anymore. In fact, you’re depending on credit cards to put food on the table.

Don’t expect to live that long? Think again! Life expectancy is currently in the mid-80s and medical technology is stretching that each year. A couple reaching age 65 have a 50/50 chance that at least one of them will live into their 90s. So the vast majority of us can benefit from compound interest.

What’s the point? The difference between being in good shape financially and always struggling with money isn’t that big. Often it doesn’t take a superhuman effort to put off borrowing money or to save a little, but the results for those who do make the effort can be very big. And that makes the effort very worthwhile.

• The 10 Things You Need To Know About Compound Interest
• Compound Interest for Poor People
• What You Need To Know About Compound Interest at 50+
• What Retirees (and the Nearly Retired) Need To Know About Compound Interest

Reviewed August 2023

About the Author

Gary Foreman is the former owner and editor of The Dollar Stretcher. He's the author of How to Conquer Debt No Matter How Much You Have and has been featured in MSN Money, Yahoo Finance, Fox Business, The Nightly Business Report, US News Money, Credit.com and CreditCards.com.