APR is the yearly interest rate, but you only pay it on the balance you carry from month to month
APR stands for Annual Percentage Rate. It is the interest rate a credit card company charges you for borrowing money. If your card has a 20% APR and you carry a $1,000 balance for a full year without paying it down, you will owe roughly $200 in interest charges on top of that $1,000.
The key word is "annual" — the APR is stated as a yearly rate, but credit card companies calculate and charge interest monthly. They divide your APR by 12 to get a monthly rate, then apply that to whatever balance you owe at the end of each billing cycle. If you pay your full balance by the due date, you pay no interest at all, regardless of how high your APR is.
Most credit cards charge different APRs for different types of transactions. A purchase APR applies to everyday spending. A cash advance APR — which is what you pay when you withdraw cash using your card — is almost always higher and starts accruing interest immediately, with no grace period. A balance transfer APR applies if you move debt from one card to another.
Key Takeaways
- APR is a yearly rate divided into monthly charges; you only pay interest on balances you carry past your due date, not on purchases you pay off in full.
- Different APRs apply to purchases, cash advances, and balance transfers, and cash advance rates are typically 5 to 10 percentage points higher than purchase rates.
- Your actual APR depends on your credit score and creditworthiness; the rate shown in an offer is not may provide until the card issuer reviews your application.
- Introductory 0% APR offers last for a set period (usually 6 to 21 months) and apply only to the type of transaction specified in the offer, then revert to the standard APR.
- Interest compounds daily on most cards, meaning unpaid interest gets added to your balance and then charged interest itself the next day.
How the monthly interest charge is calculated
Credit card companies use one of two methods to calculate your monthly interest: the average daily balance method or the adjusted balance method. Most use average daily balance, which is more common and usually results in higher interest charges.
With the average daily balance method, the company adds up your balance for each day of the billing cycle, then divides by the number of days in that cycle. They apply your monthly interest rate (your APR divided by 12) to that average. So if your APR is 18% and your average daily balance over 30 days was $2,000, your monthly interest charge would be roughly $30 (18% ÷ 12 = 1.5% per month; 1.5% × $2,000 = $30).
The adjusted balance method is simpler but less common: the company takes your balance at the end of the billing cycle, subtracts any payments you made during that cycle, and charges interest on what remains. This method usually costs you less in interest.
Your statement should disclose which method your card uses. If you cannot find it, call the card issuer's customer service number on the back of your card and ask.
Why your APR might be different from the advertised rate
When a credit card company advertises an APR, that rate is not may provide. It is a range, and the actual rate you receive depends on your credit score, payment history, income, and other factors the issuer considers when reviewing your application.
A person with a credit score above 750 might receive the advertised 15% APR, while someone with a score of 650 might receive 22% on the same card. The issuer is legally required to disclose the range of APRs you might receive before you apply, usually in fine print or in a separate disclosure document.
Your APR can also change after you open the account. Most cards have a variable APR, which means the rate moves up or down based on changes to the prime rate set by the Federal Reserve. When the Fed raises rates, your APR typically rises within one or two billing cycles. Your card issuer must give you at least 45 days' notice before increasing your APR, and they must explain the reason in writing.
Introductory 0% APR offers and what happens when they end
Many credit cards offer a 0% APR for a limited time — typically 6 to 21 months — on purchases, balance transfers, or both. During this period, you pay no interest on that type of transaction, even if you carry a balance.
The catch is that the 0% rate applies only to the transaction type specified in the offer. If your card offers 0% on purchases for 12 months but you do a balance transfer, that balance transfer is charged the regular balance transfer APR immediately. Similarly, if you make a purchase after the 0% period ends, that purchase is charged the regular purchase APR going forward.
When the introductory period expires, any remaining balance on the covered transaction type reverts to the standard APR listed in your card agreement. If you had a $3,000 balance transfer at 0% for 12 months and still owed $2,500 when the period ended, that $2,500 would suddenly start accruing interest at your card's regular balance transfer APR — often 25% or higher.
To avoid surprise interest charges, mark your calendar for the day your 0% period ends and plan to pay down or transfer the balance before that date.
How interest compounds and why balances grow faster than you expect
Credit card interest compounds daily on most cards. This means unpaid interest gets added to your balance, and then you are charged interest on that interest the next day.
Here is how it works in practice: suppose you have a $5,000 balance with an 18% APR and you make no payments. On day one, the company calculates one day's worth of interest (18% ÷ 365 = about 0.049% per day; 0.049% × $5,000 = about $2.45). That $2.45 is added to your balance, making it $5,002.45. On day two, interest is calculated on $5,002.45, not just the original $5,000. Over a month, this compounds into roughly $75 in interest charges. Over a year, it compounds into roughly $973 — nearly 20% of your original balance.
This is why carrying a balance is expensive: you are not just paying interest on what you borrowed; you are paying interest on the interest itself.
The difference between APR and effective annual rate
APR and effective annual rate (sometimes called annual percentage yield, or APY) are not the same thing, though credit card companies often use the terms loosely.
APR is the simple yearly rate before compounding. Effective annual rate accounts for the fact that interest compounds — it is the true cost of borrowing when you factor in daily compounding. On a credit card with an 18% APR, the effective annual rate is closer to 19.7% because of daily compounding.
For credit cards, the APR is what matters for comparison purposes, because federal law requires all card issuers to disclose APR the same way. But understanding that the effective rate is higher helps explain why your balance grows faster than a simple percentage calculation suggests.
Frequently Asked Questions
Do I pay APR if I pay my balance in full each month?
No. If you pay your entire statement balance by the due date, you pay no interest, regardless of your APR. The APR only applies to balances you carry past your due date. This is called the grace period — typically 21 to 25 days from the end of your billing cycle.
Why is cash advance APR so much higher than purchase APR?
Card issuers treat cash advances as riskier than purchases because they have no grace period and no consumer protections. Interest starts accruing immediately, and there is no dispute process if something goes wrong. The higher rate reflects that risk. Cash advance APRs are often 5 to 10 percentage points higher than purchase APRs on the same card.
Can a credit card company raise my APR whenever they want?
No. They must give you at least 45 days' notice in writing before raising your APR, and they must explain the reason. They can raise a variable APR when the prime rate changes, but they cannot raise a fixed APR without notice. You have the right to reject the increase and close your account, though you will still owe the balance at the old rate.
What happens to my APR if I miss a payment?
Your card issuer can raise your APR if you miss a payment by 60 days or more. This is called a penalty APR and can be significantly higher than your regular rate. However, if you make on-time payments for six months after missing one, the issuer must lower your APR back to the regular rate.
Is a lower APR always better when choosing a credit card?
Not necessarily. If you plan to pay your balance in full each month, APR does not matter at all — you will pay no interest regardless. If you do carry a balance, a lower APR saves you money, but other factors matter too: annual fees, rewards rates, and whether the card offers a 0% introductory period. Compare the total cost, not just the APR.