How to Calculate Credit Card Interest: 3 Steps to Find Your Rate (2026)

One of the most important factors in choosing a credit card is its interest rate, and it’s also important to know how to calculate credit card interest. All credit cards must disclose their annual percentage rate, or APR, which expresses their interest rates in a single annual number. Almost all credit cards charge interest only on balances that you don’t fully pay off in the most current billing cycle. But how does APR translate into the amount of interest you’ll actually pay?

Read on to learn more about, including an in-depth look at how you can find your daily periodic rate, simple versus compound interest, how to calculate your average daily balance, and more. Or skip ahead to learn how your APR is calculated or to compare the best balance transfer offers to avoid paying interest.

Before we can explain the first step, we should clarify a few important terms:

Grace Period: The normal billing cycle for a credit card can range from 28 to 31 days. The due date for your monthly payment is no less than 21 days after the end of the billing cycle. Each billing cycle provides a grace period, which means you don’t incur interest on purchases made within the billing cycle if you pay them in full by the due date. Your outstanding balance is the accumulated amount you haven’t paid within a grace period.

Simple Versus Compound Interest: Simple interest is the amount you pay on your outstanding balance without including the effect of compounding. Virtually all cards figure your interest with compounding, which means they add the interest you already owe to the amount subject to interest – you are paying interest on interest.

In the good old days, credit cards used monthly compounding, but the current fashion is daily or continuous compounding, which will cost you more. As an example of daily compounding, if your outstanding balance is $1,000 and the day’s interest is 71 cents, then tomorrow’s outstanding balance will be $1,000.71 (assuming no other purchases or payments).

Nominal Versus Effective APR: When you see an ad for a credit card, the interest rate is expressed as the nominal APR, which is based on simple interest and excludes fees. The more appropriate number is the effective APR, which includes the effects of compounding and any fees that are not paid separately. Some cards charge the annual fee (if any) as a lump sum, but others spread the annual fee over the entire year, making it part of the effective APR.

If possible, obtain the effective APR of any credit card you are considering. Fees for late payments or for exceeding your credit limit are not included in any APR, since they are charged separately.

To illustrate the three-step process for calculating your interest charges, imagine that you have an outstanding balance of $3,500 on a credit card with an interest rate of 25 percent.

In this example, the credit card uses a 360-day year (some cards use 365, terms will vary), so the daily percentage rate, or DPR, is equal to 25% / 360, or .06944%. This is the interest rate you pay each day on the balance subject to interest. Assuming daily compounding and no other activity, your daily balance would grow each day by the interest charged on the previous day.

The average daily balance is computed by adding together each day’s outstanding balance and dividing by the number of days in the billing period. For simplicity’s sake, we set the average daily balance to $3,500.

Finally, we calculate the interest charged for the billing cycle, which in this example, is $3,500 x .06944% x 30 days, or $72.91. This is the amount of interest you would be charged on a card with a $3,500 balance and a 25% interest rate.

The APR on your credit card is based on the bank’s opinion of your creditworthiness, which is in large part derived from your credit score. Most banks use FICO credit scores, which range from 300 (the worst) to 850 (the best).

Each of the three major credit bureaus, Equifax, Experian, and TransUnion figure their FICO scores a little differently, but the scores tend to cluster closely. Interpretations differ, but generally, 700 is considered the dividing line between good and fair scores. The lower the score, the higher APR you’ll pay. If your score is too low, you could have difficulty qualifying for any credit at all.

Sometimes, banks will take into account other factors when determining your APR, such as black marks on your credit history (bankruptcies, court decisions, garnished wages, etc.). You will save money on interest if you can raise your FICO score – check out the myFICO website for tips on how to do that.

Many credit cards offer special balance transfer deals that can save you money. In a balance transfer, you move your outstanding balance from one credit card to another. To entice new customers, the balance transfer offers usually include a set number of months during which you don’t owe any interest on the transferred amount.

Some of the best balance transfer offers grant interest-free periods of 15 or even 21 months. In addition, some cards will also grant a multi-month grace period on new purchases made after you transfer a balance. If you combine that with a zero-percent annual fee and a reasonably low APR, you have the makings of a great credit card. Here are some of our favorites:

BankAmericard® credit card

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BankAmericard® credit card

4.6/5.0

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Our experts rate credit card offers based on factors like rewards, APRs, signup bonuses, fees, and approval rates, with a focus on benefits that provide the best value. We also consider cardholder needs such as credit-building potential, issuer reputation, and customer service. Our ratings are unbiased, updated regularly, and not influenced by issuers.

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★★★★★ 4.6/5.0

at Bank Of America'ssecure website

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• New! 0% Intro APR for 21 billing cycles for purchases, and for any balance transfers made in the first 60 days. After the Intro APR offer ends, a Variable APR that’s currently 14.99% - 25.99% will apply. A 5% fee applies to all balance transfers. Balance transfers may not be used to pay any account provided by Bank of America.
• No annual fee.
• No penalty APR. Paying late won't automatically raise your interest rate (APR). Other account pricing and terms apply.
• This offer may not be available elsewhere if you leave this page. You can take advantage of this offer when you apply now.

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Intro (Purchases) 0% Intro APR for 21 billing cycles for purchases

Intro (Transfers) 0% Intro APR for 21 billing cycles for any balance transfers made in the first 60 days (Balance Transfer Fee 5% of the amount of each transaction)

Regular APR 14.99% - 25.99% Variable APR on purchases and balance transfers

Annual Fee $0

Credit Needed Excellent/Good

Citi® Diamond Preferred® Card

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Citi® Diamond Preferred® Card

4.5/5.0

About this rating

Our experts rate credit card offers based on factors like rewards, APRs, signup bonuses, fees, and approval rates, with a focus on benefits that provide the best value. We also consider cardholder needs such as credit-building potential, issuer reputation, and customer service. Our ratings are unbiased, updated regularly, and not influenced by issuers.

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★★★★★ 4.5/5.0

at Citi'ssecure website

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• 0% Intro APR on balance transfers for 21 months and on purchases for 12 months from date of account opening. After that the variable APR will be 16.49% - 27.24%, based on your creditworthiness. Balance transfers must be completed within 4 months of account opening.
• There is an intro balance transfer fee of 3% of each transfer (minimum $5) completed within the first 4 months of account opening. After that, your fee will be 5% of each transfer (minimum $5).
• No Annual Fee - our low intro rates and all the benefits don't come with a yearly charge.
• Buy now and pay later. Split your payment for eligible purchases of $75 or more into a fixed payment with Citi® Flex Pay.
• Get free access to your FICO® Score online.

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Intro (Purchases) 0% 12 months on Purchases

Intro (Transfers) 0% 21 months on Balance Transfers

Regular APR 16.49% - 27.24% (Variable)

Annual Fee $0

Credit Needed Good/Excellent

See Rates & Fees »

BankAmericard® credit card for Students

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BankAmericard® credit card for Students

4.5/5.0

About this rating

Our experts rate credit card offers based on factors like rewards, APRs, signup bonuses, fees, and approval rates, with a focus on benefits that provide the best value. We also consider cardholder needs such as credit-building potential, issuer reputation, and customer service. Our ratings are unbiased, updated regularly, and not influenced by issuers.

See Our Review»

Ashley Fricker Senior Editor

Close

★★★★★ 4.5/5.0

at Bank Of America'ssecure website

Our Review »

• New! 0% Intro APR for 21 billing cycles for purchases, and for any balance transfers made in the first 60 days. After the Intro APR offer ends, a Variable APR that’s currently 14.99% - 25.99% will apply. A 5% fee applies to all balance transfers. Balance transfers may not be used to pay any account provided by Bank of America.
• No annual fee.
• No penalty APR. Paying late won't automatically raise your interest rate (APR). Other account pricing and terms apply.
• When handled responsibly, a credit card can help you build your credit history, which could be helpful when looking for an apartment, a car loan, and even a job.
• This offer may not be available elsewhere if you leave this page. You can take advantage of this offer when you apply now.

Show MoreShow Less See application, terms and details »

Intro (Purchases) 0% Intro APR for 21 billing cycles for purchases

Intro (Transfers) 0% Intro APR for 21 billing cycles for any balance transfers made in the first 60 days (Balance Transfer Fee 5% of the amount of each transaction)

Regular APR 14.99% - 25.99% Variable APR on purchases and balance transfers

Annual Fee $0

Credit Needed Excellent/Good

Discover it® Chrome

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Discover it® Chrome

4.8/5.0

About this rating

Our experts rate credit card offers based on factors like rewards, APRs, signup bonuses, fees, and approval rates, with a focus on benefits that provide the best value. We also consider cardholder needs such as credit-building potential, issuer reputation, and customer service. Our ratings are unbiased, updated regularly, and not influenced by issuers.

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★★★★★ 4.8/5.0

at Discover Card'ssecure website

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• INTRO OFFER: Unlimited Cashback Match for all new cardmembers. Discover will automatically match all the cash back you’ve earned at the end of your first year! There’s no minimum spending or maximum rewards.
• Earn 2% cash back at Gas Stations and Restaurants on up to $1,000 in combined purchases each quarter, automatically. You'll still earn unlimited 1% cash back on all other purchases.
• Get a 0% intro APR for 18 months on balance transfers. Then 17.49% to 26.49% Standard Variable APR applies, based on credit worthiness.
• Redeem cash back for any amount
• No annual fee.
• Terms and conditions apply.

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Intro (Purchases) 0% Intro APR for 6 months

Intro (Transfers) 0% Intro APR for 18 months

Regular APR 17.49% - 26.49% Variable APR

Annual Fee $0

Credit Needed Excellent/Good

See Rates & Fees »

Citi Double Cash® Card

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Citi Double Cash® Card

4.8/5.0

About this rating

Our experts rate credit card offers based on factors like rewards, APRs, signup bonuses, fees, and approval rates, with a focus on benefits that provide the best value. We also consider cardholder needs such as credit-building potential, issuer reputation, and customer service. Our ratings are unbiased, updated regularly, and not influenced by issuers.

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Ashley Fricker Senior Editor

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★★★★★ 4.8/5.0

at Citi'ssecure website

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• Earn $200 cash back after you spend $1,500 on purchases in the first 6 months of account opening. This bonus offer will be fulfilled as 20,000 ThankYou® Points, which can be redeemed for $200 cash back.
• Earn 2% on every purchase with unlimited 1% cash back when you buy, plus an additional 1% as you pay for those purchases. To earn cash back, pay at least the minimum due on time. Plus, earn 5% total cash back on hotel, car rentals and attractions booked with Citi Travel.
• Balance Transfer Only Offer: 0% intro APR on Balance Transfers for 18 months. After that, the variable APR will be 17.49% - 27.49%, based on your creditworthiness.
• Balance Transfers do not earn cash back. Intro APR does not apply to purchases.
• If you transfer a balance, interest will be charged on your purchases unless you pay your entire balance (including balance transfers) by the due date each month.
• There is an intro balance transfer fee of 3% of each transfer (minimum $5) completed within the first 4 months of account opening. After that, your fee will be 5% of each transfer (minimum $5).

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Intro (Purchases) N/A

Intro (Transfers) 0% 18 months on Balance Transfers

Regular APR 17.49% - 27.49% (Variable)

Annual Fee $0

Credit Needed Excellent/Good

See Rates & Fees »

+See more balance transfer cards

Now that you know how interest is calculated, you can follow this strategy to lower your interest expenses:

1. Improve your credit score
2. Shop around for a credit card that combines the lowest effective APY with the best balance transfer program
3. Transfer debt from other credit cards to your new one
4. Pay down your credit card debt during the 0% interest intro period of your balance transfer
5. Avoid accumulating outstanding balances in the future

For almost all credit cards, you’d never shell out any interest if you paid off your balance in full each month. However, some credit cards do not provide grace periods, so it’s worth the extra effort to look into this before applying. One other point – cash advances incur interest immediately and never have a grace period, so if you’re looking to avoid interest, that may not be the route for you.