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Credit Card Interest – How It’s Calculated & How To Avoid Paying It

Susan Wright's image
Susan Wright
Susan Wright's image

Susan Wright

Former Finance Contributor

17 Published Articles

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Susan earned a BA from Michigan State University and her MBA from St. Louis University and has spent more than 25 years as a financial copywriter. She holds 11 financial industry designations, includi...
Edited by: Keri Stooksbury
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Keri Stooksbury


36 Published Articles 3278 Edited Articles

Countries Visited: 47U.S. States Visited: 28

With years of experience in corporate marketing and as the executive director of the American Chamber of Commerce in Qatar, Keri is now editor-in-chief at UP, overseeing daily content operations and r...

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Receiving a credit card application can be exciting — especially if you’ve been preapproved for a card.

Credit cards can allow you to make purchases immediately, even if you don’t actually have the money in your bank account. But before you run full steam ahead into applying for any credit card, it’s absolutely critical that you understand credit card interest, how it is calculated, and how you can avoid having to pay it.

Banks and other lenders providing you the opportunity to use borrowed funds might initially sound like a great deal! But the reality is that these entities aren’t giving you anything for free — and if you’re not careful, you can end up paying quite a bit for the “opportunity” to use their money.

How Borrowing Money Really Works

Being extended credit through a credit card is essentially a process of borrowing money. In this case, the credit gives you money all at once that may not otherwise be available to you, especially if you’re making a high-dollar purchase (like a new computer or big screen TV).

Credit Comes at a Price

Credit — particularly credit that’s provided to you through credit cards — can come at a very high price.

Hot Tip: While many people don’t think of it this way, the reality is that every time you use a credit card, you’re getting a loan from the lender or creditor that issues that card. In essence, you are promising to pay back the amount you charged on the card.

Credit Card Statement
Credit can be convenient, but it can also come at a high price. Image Credit: create jobs 51 via Shutterstock

Let’s take a look at a basic example of borrowing money. Here, we’ll say that you borrowed $1,000 for 2 years with a simple interest rate of 5%. In this case, you will pay back a total of $1,100.

This is because your 5% interest rate equates to $50 per year ($1,000 x .05 = $50). You paid interest for 2 full years ($50 x 2 years = $100), plus you repaid the $1,000 in principal.

If you made these loan payments on a monthly basis, the amount of your payment would have been $45.83 ($1,100 divided by 24 monthly payments).

While this may look cut and dry, not all borrowing situations are the same — nor do all lenders and creditors charge a simple rate of interest on borrowed funds.

Though most credit cards do have a set rate of interest, if you don’t pay back the entire balance in full by the payment due date, the creditor that issued the card will not only charge you interest on the remainder of your principal balance but also on prior months’ interest charges.

That can really add up!

The Impact of Different Interest Rates

Before you take on any type of debt (especially credit card debt), it’s important that you shop around to secure the best interest rate. One reason for this is because a difference of even just half a percent could be significant in the total amount of money that you end up paying back.

As an example, take a look at 2 identical home loans, where the only difference is the interest rate. In each case, the individual is borrowing $100,000 for 30 years.

With Loan #1, the interest rate is 4.5%, while Loan #2 has an interest rate of 5%.



Monthly Payment

Total Repayment Amount

Loan #1


$506.69 x 360 months = $182,406.71

Loan #2


$536.82 x 360 months = $193,255.78

In this case, the difference in the cost of total repayment between these 2 loans was nearly $11,000, based just on the different interest rate that was charged!

Deferred vs. Standard Interest

In addition to knowing the interest rate you’re paying — and how much it can add up if you don’t pay off your credit card balance each month — it is important to know whether you’re paying standard or deferred interest because this can make a big difference.

As an example, many retailers advertise an “introductory” interest rate of 0% in order to entice consumers to apply for their credit cards. But just because you may not be charged interest for the first few months doesn’t mean that you won’t be charged interest at all.

The terms “no interest for 6 months” and “no interest if paid in full within 6 months” are 2 very different things. The latter is what’s called deferred interest.

With deferred interest, you could even end up paying more down the road if you keep a running balance on the card.

Here’s why: Let’s say that you apply for a store credit card, where the interest rate is normally 26.24%. When you initially apply for the card, though, the retailer offers you 0% interest for a specified promotional period if your balance is paid in full within that time.

This might sound like a great deal — and it could be, provided that you don’t carry a balance on the card and pay it off in full within the promotional period. However, if you don’t, interest charges will be imposed on the starting balance at the APR for regular purchases retroactively from the date of purchase. 

That’s because, with this type of financing, the interest on the purchases you make with the card isn’t waived. Rather, it is deferred unless you pay your balance in full. Essentially, it is continuing to rack up — even during your promotional 0% interest rate period.

In cases like this, it can definitely be to your advantage to pay off the entire balance before the promotional period ends. Otherwise, you will be charged interest retroactively (in this example, at a rate of 26.24%) starting from the initial purchase date.

Another thing to consider? Some people think by paying only their minimum payments, they’ll achieve a zero balance by the end of the promotional period. Sadly, oftentimes this isn’t the case so individuals who think they’ve been acting as a responsible cardholder get a big surprise when deferred interest is applied.

Bottom Line: Know your terms when it comes to special financing! The difference between “no interest for 6 months” and “no interest if paid in full within 6 months” is a big one! 

Interest Rate and APR Are Not the Same — And Why It Matters

While you might be familiar with how interest rates work in borrowing situations, the APR (or Annual Percentage Rate) can often seem confusing. In its most basic sense, an interest rate is the “price” that is paid for borrowing money.

When it comes to credit cards, though, interest rates are often stated as annual rates. This is referred to as the Annual Percentage Rate (APR).

The APR takes into account the total cost of borrowing money from the credit card issuer, which can encompass the interest rate as well as other fees that you incur.

The Dangers of Borrowing Too Much

Today, it’s rare for people to carry around a great deal of cash in their pockets. Instead, using credit can make transactions of nearly any size much quicker and more convenient. Unfortunately, though, borrowing too much can end up being hazardous to your financial health.

Because credit cards often have a nice-sized limit, it can be much easier to purchase on impulse as opposed to having a budget for the item or service.

Bottom Line: Having too much debt can also make it much more difficult to pay off your balance in full each month, which can end up costing you a lot.

Are You Becoming Trapped by Credit Card Debt?

When it comes to borrowing for purchases like a car or a home, credit cards work a bit differently than these types of loans. But, rather than having a standard repayment amount each month, the amount you owe on a credit card balance can continue to grow due to compounding interest — even if you don’t make any additional purchases.

Credit Card Shark
Using credit cards wisely can help keep debt under control. Image Credit: James Steidl via Shutterstock

How Credit Card Interest Is Calculated

Let’s take a look at how credit card interest is determined, and how it can start to snowball out of control if you don’t pay off the balance each month.

In this example, let’s say you purchased some new clothes for $100 on the first day of the month and used a credit card to pay for them.

At the end of the month, your credit card statement arrives (for the sake of this simple example, let’s assume that this $100 clothing purchase is the only time you used your credit card that month).

But the credit card company is nice enough to let you make only a minimum payment of say, $10. Wanting to hold on to as much of your cash as possible, you go ahead and make just the minimum payment on the card on the due date.

Using basic math, you would think that a $100 initial balance minus your $10 payment means you now owe the credit card company $90, but this isn’t actually how credit card debt works!

Depending on the credit card company and other factors such as your credit score (a higher credit score usually means a lower interest rate and vice versa), you may find that the interest rate charged on your balance is in the neighborhood of 20% or higher!

There are a few primary ways that credit card companies calculate interest, but we’ll use the simplest one — the daily average balance method.

Credit card companies will average your balance for every day of the month, then multiply that by the daily rate and the number of days in the billing cycle to determine your interest owed.

There are 3 pieces of information you will need to know to make this calculation:

  1. Your daily periodic rate, or DPR
  2. Your average balance on your card
  3. Days in the billing cycle

Daily Periodic Rate

Since an APR is an annual rate, your credit card issuer will divide that number by 365 to determine a daily interest rate. If your APR is 20%, for example, the daily rate would be 0.054% (or 0.000548).

Hot Tip: Some cards use 360 days, so be sure to check your specific terms.

Average Balance

As we mentioned above, you’ve spent $100 on the first day of the month. You use the previous month’s daily average balance in order to calculate the interest owed in the current month, so it would be $100.

This obviously gets a bit more complex once you factor in interest owed and minimum payments made, so we’ll walk you through the next month, too.

Your starting balance in month 2 is still $100 since you haven’t made a payment. Let’s say you made that payment on the 15th day of the month. You also have to factor in the interest owed as well. That would mean that your average daily balance for month 2 is:

((100*15 days)+(91.64*15 days))/30 days = $95.82

Days in Statement Period

Let’s keep it simple and assume all months have 30 days.


To calculate your interest fees for the month, your credit card issuer multiplies the average daily balance by the number of days by the DPR.

$100 average balance x 30 days x 0.000548 DPR = $1.64 in interest owed

The total balance you now owe after your $10 payment is $91.64. Let’s run with this example to see how it plays out in later months.

Example of Credit Card Interest Accumulation


At this rate, it would take you a little over 12 months to pay off this debt and you would have incurred over $11 in interest (or more than 10% of your original item).

Other credit card issuers use a method called Daily Balance for calculating interest. With this method, interest is calculated based on your balance on each individual day in your billing period.

Interest can be compounded daily or monthly for this method, depending on the terms of your card (which will result in even higher rates than our example above!).

To find out exactly how interest is calculated on your credit card, be sure to read your cardholder agreement. 

The key here is not to let your credit card balances get out of hand.

If possible, try to pay them in full each month. Otherwise, it could equate to a very high-interest loan on items that are not likely to increase in value.

The Different Types of Credit Card Fees and Charges

Some of the most common credit card fees and charges include:

Annual Percentage Rate (APR)

As discussed above, the Annual Percentage Rate, or APR, is the cost of borrowing money on an annual basis. If you’re late in making your monthly payment to the credit card issuer, you may find that they will increase your APR.

Cut up credit card
Interest rate is just one of the many fees you may find on your credit card statement. Image Credit: gemphoto via Shutterstock

Annual Fee

Some credit cards come with an annual fee just for the privilege of using them. This fee could be $50, $100, or even more. While you may not like paying an annual fee, some credit cards can be well worth it if they offer attractive rewards.

Late Fee

If you do not make your credit card payments on time, you can be hit with a late fee. These fees are typically in the range of $30 to $50 per occurrence, but they could be more depending on the card.

To avoid the late fee — and a potential rise in your interest rate — be sure to make your credit card payment on time each month.

Over-limit Fee

Credit card companies will almost always put a limit on how much credit you can use. If you go over this limit, the card company will typically charge you a fee (usually called an “over-limit fee”).

Bottom Line: Before you make any large purchases or a number of smaller purchases, make sure that you know exactly what your credit limit is.

Cash Advance Fee

There are many credit cards today that will allow users to take a cash advance. In fact, some card companies even advertise this by sending users “checks” in the mail that simply need to be signed and cashed.

But before you rush to your local bank or ATM, you should know that most credit cards will charge you a fee for this type of transaction. That fee is in addition to the interest you will be charged on your outstanding balance until you have repaid the cash advance.

How Too Much Credit Card Debt Can Impact Your Credit

Using credit cards wisely by making timely payments each month can help you raise your credit score. But just the opposite can also be true: having too much credit card debt can negatively impact both your credit score and your credit report.

Your FICO score is used in more than 90% of U.S. lending decisions, so it’s important to gain (and keep) a high FICO score to improve your odds of credit approval and being eligible for the most attractive interest rates.

There are 5 categories considered when determining your overall credit score. Each of these carries a different percentage weighting in terms of importance. These include:

  • Payment history: 35%
  • Amount of debt: 30%
  • Length of your credit history: 15%
  • New credit: 10%
  • Credit mix: 10%

As you can see, nearly a third of your overall credit score is based on how much debt you carry. This particular component of your score includes several factors, such as:

  • The total balance you owe
  • How many of your accounts have balances
  • How much of your available credit you are using

Hot Tip: The specific types of accounts where you owe money are also taken into consideration. For example, if you owe $50,000 on a home mortgage, it is considered much more favorably than if you owe $50,000 on a credit card — especially if you are at or near your total credit limit.

Tips for Using Credit Cards to Your Advantage

Having 1 or more credit cards can provide numerous benefits. In addition to allowing for quick and convenient transactions, many cards now offer various points, rewards, and/or cashback on purchases.

But spending too much money on your credit card or not paying off your balance every month can end up being costly. By following some helpful tips, you can get into good habits and learn to use credit cards to your advantage.

Start Small

If you don’t have any prior experience with credit cards, be sure to start small. In other words, don’t charge too much at once, and make sure you can pay off the full balance amount when you receive your statement each month.

Make Your Payment on Time

Always pay your credit card bill on time, even if you are not able to make the full amount. Timely payments can significantly impact your score, too; in this case, it’s better to leave a balance on your card than reduce your credit score by making your payment late (while also incurring a late fee from the credit card company).

Hot Tip: If you’re in a real bind and need more time to clear off your balance and therefore reduce your interest payments, then you could look into transferring your balance to a credit card with 0% intro APR on balance transfers.

Determine Needs vs. Wants

When it comes to making purchases, having a credit card can definitely open up a whole new array of options. Unfortunately, this can result in a sizable balance each month, often racked up for items you really don’t need.

With that in mind, make sure to only purchase items you truly need with your card and ensure you can make the payment when it comes due. Otherwise, you may need to forgo certain purchases.

Don’t Sign up for Unneeded Credit Cards

While it may be nice to receive a “free welcome bonus” that is being offered by a credit card issuer, be careful. If a card vendor asks you to apply for their card, keep in mind that doing so will typically require the company to check your credit, which can result in lowering your credit score.

credit card application form
Filling out a credit card application can result in your credit score going down. Image Credit: via Shutterstock

Cut up or Hide Your Credit Card(s)

In extreme scenarios, you may need to consider cutting up or hiding your card(s) so you don’t make any more purchases on credit. Even though doing so can make your financial life a bit less convenient, it can also help ensure that you don’t rack up any more charges (and the corresponding interest) on your card(s).

When It Makes Sense To Use a Credit Card (and When It Doesn’t)

Using credit cards to make purchases can offer ease and convenience. But just like most other things in life, there are times when it can make sense to use credit cards… and times when it doesn’t.

Overall, it can make sense to use a credit card if:

  • You are able to pay off your balance in full each month
  • The rewards you’re accumulating are worth more than the cost of the card
  • You want additional fraud protection on your purchases
  • You want to build or improve your credit score

Alternatively, it can make sense not to use credit if:

  • You already have a considerable amount of credit card debt
  • Using a credit card would only add to your debt balance(s)
  • You are working hard to stick to a budget and be more mindful of your spending habits

In these cases, using cash or debit could be more beneficial for you.

Hot Tip: If you’re unsure of the differences, see our article on debit cards vs. credit cards to learn which may be best for you.

Final Thoughts

Credit cards can allow you to make more (and larger) purchases without the need to apply for a loan, and without having to wait until you have enough money in the bank to pay cash for an item or a service.

But when you use credit cards, it’s also imperative to look out for interest and other charges, as these can make the cost of your actual purchase much higher. Using the right type of credit card responsibly can benefit you in many ways, including the accumulation of various points or rewards.

Frequently Asked Questions

How is interest charged on credit cards?

In most cases, credit card issuers will multiply the current balance by the daily rate in order to determine the daily interest charge. That charge will then be added to the balance the following day. This process is referred to as compounding interest.

How can you avoid having to pay interest on your credit card?

The best way to avoid paying interest on your credit card is to pay off the balance in full every month. You can also avoid other fees, such as late charges, by paying your credit card bill on time.

Does everyone have the same interest rate on their credit card?

No, the interest rate you are charged can vary from one credit card to another and from one person to another depending on factors such as credit history and credit score.

In addition, certain cards will have higher (or lower) interest rates. The better your credit history, the better cards (and lower interest rates) you will qualify for.

What is a grace period and how does it work?

Some credit card companies will grant a grace period for payment receipt. If a grace period applies to your credit card, then the card issuer won’t charge you interest if you pay the entire balance by the due date of this period.

What is a good interest rate on a credit card?

While rates vary by card and issuer, ultimately the best interest rates are available to those with good to excellent credit.

The average interest rate for new credit cards is around 16%, but if you have excellent credit, you may be able to qualify for interest rates at or below 14%. If your credit is lower, somewhere close to 25% may be what you qualify for.

Susan Wright's image

About Susan Wright

While writing about finance and insurance isn’t something that keeps most people awake at night, it is what Susan Wright has focused on for more than 25 years. As a financial copywriter, Susan has an eye for money-related details such as credit and savings, and she loves to pass along helpful information to consumers. Susan holds 11 financial industry designations (including CLU, ChFC, RHU, REBC, ADPA, CITRMS, CIPA) as well as several licenses.


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