Tool guide

Credit Card Interest: How It Works and How It's Charged

Credit card interest is often charged daily: your APR divided by 360 or 365, times each day's balance. How grace periods, cash advances and payments change it.

Updated October 6, 20267 min readReviewed by Netanel Baruch, NFCC-certified credit counselor

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How credit card interest works
How to calculate credit card interest yourself
The grace period: how to pay no interest at all
Why one card can have several interest rates
Which balance your payment goes to
When your interest rate can go up
How to pay less credit card interest
Bottom line
Common questions
Sources

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Credit card interest is what the card company charges you for carrying a balance, and many companies work it out every day. They divide your APR by 360 or 365 to get a daily rate, multiply that rate by each day's balance, and add the result to what you owe (CFPB: What is a daily periodic rate on a credit card?). Pay your full statement balance by the due date on a card with a grace period, and new purchases usually cost no interest at all.

How credit card interest works

Your card's interest rate is quoted as an APR, an annual percentage rate. Card companies don't charge it once a year. The CFPB says many credit card companies calculate the interest you owe daily, based on your average daily account balance. The rate they apply each day is called the daily periodic rate.

To get it, the company divides the APR by 360 or 365, depending on which it uses. Then, in the CFPB's words, the daily rate is multiplied "by the amount owed at the end of each day". That day's interest is added to the balance, so tomorrow's interest is charged on today's interest too. The CFPB calls this interest "compounding on a daily basis."

Whether your company uses 360 or 365 days makes only a small difference. On the example below, 360 days comes to about $63 for the cycle instead of $62.

How to calculate credit card interest yourself

You need four numbers: your balance, your APR, the number of days in the billing cycle, and whether your company divides by 360 or 365. If you can't find the last one, ask your card company.

Divide the APR by 365 (or 360). At 24.99%, that's 0.2499 ÷ 365 = 0.000685, about 0.0685% a day.
Multiply the daily rate by that day's balance. On $3,000, that's about $2.05.
The $2.05 joins the balance, and the next day's interest is charged on $3,002.05.
Repeat that for every day in the cycle. A payment lowers the balance from the day it posts. A new purchase raises it.

Here's what our credit card interest calculator shows for a $3,000 balance at 24.99% APR over a 30-day cycle, dividing by 365:

	No payment during the cycle	$200 paid on day 15
Daily periodic rate	0.0685%	0.0685%
Interest for the cycle	$62.23	$60.03

Without daily compounding, the same cycle would cost $61.62, so compounding adds about 61 cents here. It matters more over many months on a large balance. The $200 paid halfway through the cycle saves about $2.20 of interest in that cycle alone, and it keeps saving every month after because the balance is lower. Paying earlier in the cycle saves a little more.

For a rough monthly figure, multiply the balance by the APR and divide by 12. That gives $62.48 here, close to the daily figure. Our payoff tools use this shortcut.

The grace period: how to pay no interest at all

A grace period is the time between the end of a billing cycle and the date your payment is due. If you pay your balance in full by the due date, you may not be charged interest. Card companies aren't required to offer one, but the CFPB says most cards give a grace period on purchases.

A few things catch people out:

Grace periods usually cover purchases only. For cash advances and the checks your card company sends you, you generally start paying interest as of the date of the transaction.
Carrying a balance can switch it off. The CFPB says the grace period usually applies only to new purchases when you're not already carrying a balance. Once you carry a balance, new purchases can start costing interest right away.
Getting it back takes time. If you pay in full some months and not others, you may lose your grace period for the month you don't pay in full and for the month after. That's why a bill paid in full can still show interest.

The law limits what a company can charge when you lose a grace period. Under Regulation Z § 1026.54, a card company can't charge interest based on balances from billing cycles before the most recent one, and it can't charge interest on the part of a balance you repaid before the grace period ended.

Why one card can have several interest rates

A single card can carry several balances, each with its own APR. Your statement has to show each type of balance that has a different APR, with the amount in each. Purchases and cash advances are common examples.

Cash advances are usually the most expensive. The CFPB says you'll commonly pay a higher interest rate for a cash advance than for a typical purchase, interest starts as soon as you withdraw the money, and the company may also charge a flat fee or a percentage of the advance.

Which balance your payment goes to

Under Regulation Z § 1026.53, when you pay more than the minimum, the card company must put the extra toward the balance with the highest APR first, then work down from the highest rate to the lowest. There's an exception for deferred-interest promotions: in the last two billing cycles before one ends, extra payments go to that promotional balance first.

The rule only covers the amount above the minimum. Pay only the minimum, and a cheap balance-transfer balance can soak up your payment while a cash advance keeps growing at the higher rate.

When your interest rate can go up

Your rate isn't fixed forever, but the rules limit when it can rise. According to the CFPB:

The company generally must give you 45 days' notice before raising the rate on new purchases.
It generally can't raise the rate on new transactions during the first year of the account.
On existing purchases, the rate can generally go up only in a few listed cases. The main ones: a temporary rate ends, your variable rate follows its index (for example, the U.S. Prime Rate) up, or your minimum payment is more than 60 days late.
If a penalty rate kicked in because you were more than 60 days late, the company must restore your old rate after six consecutive on-time minimum payments.

For a sense of typical rates, the Federal Reserve's G.19 Consumer Credit release of September 8, 2026 shows an average of 22.15% on credit card accounts assessed interest at commercial banks in the second quarter of 2026. Your own rate is the one on your statement.

How to pay less credit card interest

These cost nothing and don't need a new account:

Pay the statement balance in full whenever you can, so the grace period keeps working.
Pay more than the minimum. Every extra dollar lowers the balance that the daily rate is applied to. Our minimum-payment calculator shows how far apart the two paths end up.
Pay earlier in the cycle, or split the payment in two, so the balance is lower for more days.
Stop using cash advances and the convenience checks your card company mails you.
Ask your card company about a lower rate or a hardship program if you're struggling. See how to get out of credit card debt for what to ask.

If you have more than one card, put extra money toward the highest APR first and you'll pay the least interest. Paying the smallest balance first gets cards closed sooner. Debt avalanche vs snowball compares the two. If your balances are large compared with your income, how to pay off $10,000 in credit card debt walks through a plan with real numbers. Paying balances down also lowers your credit utilization.

Bottom line

With many cards, interest is charged daily on whatever you owe, and it compounds. If your card has a grace period and you aren't carrying a balance, paying the full statement balance by the due date means no interest on new purchases. When you can't, every dollar above the minimum, and every day earlier you pay it, lowers the cost. Cash advances cost the most, so leave them alone. If you're carrying balances you can't clear, the Debt Check compares your options, starting with the ones that cost the least.

Common questions

How is credit card interest calculated?

Many card companies charge it daily. They divide the APR by 360 or 365 to get a daily periodic rate, multiply it by each day's balance, and add that day's interest to the balance, so interest compounds daily.

How do I avoid paying interest on a credit card?

If your card has a grace period and you aren't carrying a balance, paying the full statement balance by the due date means no interest on new purchases. Cash advances usually start charging interest the day you take them, grace period or not.

Why was I charged interest after I paid my balance in full?

If you carried a balance the month before, you may have lost the grace period. The CFPB says that if you pay in full some months and not others, you may lose the grace period for the month you don't pay in full and for the month after.

Which balance does my payment go to first?

Under Regulation Z, the card company must apply any amount above the minimum payment to the balance with the highest APR first, then to the others from highest rate to lowest. How the minimum payment itself is applied is generally up to the card company.

Can my card company raise my interest rate?

Only in limited cases. It generally must give 45 days' notice before raising the rate on new purchases, and it can't raise the rate on new transactions in the first year of the account. Being more than 60 days late can trigger a penalty rate on the existing balance.

Sources

By DebtCheckUSA Editorial Team. First published October 6, 2026. Advertiser disclosure

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