I Asked ChatGPT To Explain How Interest Rates Work Like I’m 12 — Here’s What It Said
Written by
Jordan Rosenfeld
Edited by
Molly Sullivan
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Interest rates affect many of Americans’ financial moves, yet you might not really know how they work. You’re probably most familiar with interest rates as the figure that makes your credit card bills and loans cost more money over time, but it’s a bit more complex than that.
To help clarify exactly how they work and what you need to know, I asked ChatGPT to help me understand how interest rates work as though I were 12 years old. The AI tool is good at breaking down complex details into simpler parts, and that’s just what it did.
Think of a Candy Bar
Twelve-year-olds love candy, so what better way to explain money than by breaking it down in sweet terms?
According to ChatGPT, an interest rate is just the price of money. “Just like a candy bar has a price tag, borrowing money comes with a cost — and that cost is interest, usually shown as a percentage,” it explained.
So, for example, if your “candy bar” is $100 that you borrow from the bank, and the interest you must pay in the time it takes you to return that money is 5% per year, after one year, you have to pay back $105.
“That extra $5 is the interest — the price for using their money,” ChatGPT said.
That original $100 you borrowed? That’s called the “principal.” You can think of it as the starting amount or main chunk of money. “Interest is always calculated based on that principal, and sometimes even on the interest that adds up over time, ChatGPT said.
Or, to have more fun with it, ChatGPT said, “Think of it like the base of a pizza. Everything else (like interest) gets added on top of it.”
But Why Do Interest Rates Exist?
Why do we even have interest rates? ChatGPT said it’s because “time is valuable.” More to the point, “When someone lends money (like a bank), they’re giving up the chance to use that money right now.”
So, interest is the fee you pay for the opportunity to use someone else’s money, which also happens to be a great business strategy for those who have the money to offer.
There Are Different Types of Interest
If so far interest has sounded pretty basic, it now gets just a tiny bit more complex, because there’s not just one kind of interest, but two.
Simple Interest
This type of interest is where you only pay interest on the original amount you borrowed.
Example: You borrow $100 at 5% for 3 years = $5 x 3 = $15 interest. Add that to the original $100 you borrowed, and you pay back $115
Compound Interest
Here’s where it gets more complicated. ChatGPT explained that with compound interest, “You pay interest on the original amount plus the interest that builds up over time. It’s like a snowball — it gets bigger and bigger.”
Example: You borrow $100 at 5% compound interest:
- Year 1: $105
- Year 2: $110.25 (5% of 105)
- Year 3: $115.76 (5% of 110.25)
Now you pay back $115.76 — more than simple interest.
The reason banks and other institutions use compound interest is that they make more money more quickly. You’ll likely find compound interest in:
- Credit cards: It’s typically charged daily or monthly if you don’t pay the full balance. This is why credit card debt can accumulate quickly.
- Loans with long terms (like personal or student loans): The longer window of time earns the lender more money.
- Mortgages (home loans): This also gives them more time to earn money off your loan.
The exception that benefits the average consumer is savings accounts. ChatGPT said, “This time, YOU win! Banks use compound interest to grow your savings — the more often it compounds (daily vs. yearly), the faster your money grows.”
Why Do Interest Rates Change?
You often hear that interest rates have risen or been lowered. To understand why, ChatGPT said, “Imagine the economy is like a big school.” When everyone is borrowing and spending too much, the U.S. government’s central bank, the Federal Reserve (“The Fed”), raises interest rates. “This slows things down so people don’t overspend.”
When the economy gets shaky, making people nervous about spending money or borrowing it, The Fed lowers rates to encourage more economic activity.
“It’s a way of controlling the ‘mood’ of the economy — like a volume knob on how much money is moving around,” ChatGPT explained.
Understanding more about the interest you may be saving or borrowing can help you avoid racking up debt and reap the benefit of high savings yields.
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