APR stands for Annual Percentage Rate

APR is the yearly cost of borrowing money on your credit card, shown as a percentage. If your card has a 20% APR and you carry a $1,000 balance for a full year without making payments, you will owe $200 in interest on top of the original $1,000. The APR is the single number that tells you how much interest you will pay per year.

Your card's APR is not the same as the interest charge on one month's statement. The monthly interest is calculated by dividing the APR by 12, then applying that monthly rate to your balance. A 20% APR becomes roughly 1.67% per month. That monthly rate compounds — meaning interest accrues on top of previous interest — which is why a balance carried for several months costs more than the simple math suggests.

Different balances on the same card can have different APRs. Your purchase APR (the rate on everyday spending) may be 18%, while a cash advance APR might be 25%, and a promotional APR on a transfer might be 0% for six months. Each type of transaction has its own rate, and your card issuer decides which rate applies to each payment you make.

Key Takeaways

  • APR is the annual interest rate on your credit card balance, expressed as a percentage of what you owe.
  • Your monthly interest charge is calculated by dividing your APR by 12 and applying that rate to your current balance.
  • Different types of transactions on the same card — purchases, cash advances, balance transfers — can carry different APRs.
  • Paying off your full statement balance by the due date means you pay no interest, regardless of the APR.
  • A higher APR costs you more money the longer you carry a balance, so knowing your rate helps you understand the true cost of carrying debt.

How APR is calculated into your monthly bill

Your card issuer calculates interest using your average daily balance during the billing cycle. They add up your balance for each day of the month, divide by the number of days, then multiply by your monthly rate (APR divided by 12). This is why paying down your balance mid-cycle reduces the interest you owe that month — the lower balance counts for the remaining days.

Interest compounds, meaning you pay interest on interest. If you carry a $1,000 balance at 20% APR and make no payments, after one month you owe roughly $1,016.67. In month two, interest accrues on $1,016.67, not just the original $1,000. Over time, this compounds into significantly more debt than the original balance.

Most credit cards use a method called the "average daily balance" to compute interest. A few use the "previous balance" method (interest based only on last month's ending balance) or the "adjusted balance" method (balance minus payments made during the cycle). Your card's terms document specifies which method your issuer uses. The average daily balance method is most common and typically costs you the most in interest.

Why your APR matters when you carry a balance

If you pay your full statement balance by the due date each month, your APR does not affect you — most cards include a grace period that waives interest on purchases if you pay in full. But the moment you carry a balance into the next cycle, the APR determines how much interest you owe.

A difference of just a few percentage points in APR adds up quickly on larger balances. A $5,000 balance at 15% APR costs roughly $625 per year in interest if you make no payments. The same $5,000 at 25% APR costs roughly $1,250 per year. Over two years of carrying that balance, the higher APR costs you an extra $1,250 in interest alone.

Your APR also affects how long it takes to pay off a balance if you make fixed monthly payments. A $3,000 balance at 10% APR paid at $100 per month takes about 31 months to clear. The same $3,000 at 25% APR takes about 39 months. The higher rate means more of each payment goes toward interest and less toward reducing the principal.

Fixed APR versus variable APR

A fixed APR stays the same for the life of the card or until the issuer notifies you of a change (which they must do in writing, with at least 45 days' notice). Most purchase APRs are fixed. A variable APR moves up or down based on a benchmark rate set by the Federal Reserve, usually the prime rate. When the prime rate rises, your variable APR rises automatically.

Variable APRs are common on cash advance and balance transfer offers. They are also standard on some cards marketed to people rebuilding credit. The terms document will specify whether your APR is fixed or variable and, if variable, which benchmark it tracks and how much it can move above that benchmark (called the "margin").

Even if your APR is variable, the issuer cannot raise it without notice, and they cannot apply a new rate to existing balances retroactively. A rate increase applies only to new transactions going forward. If your variable APR rises, you will see the new rate on your next statement.

Introductory APR offers and what happens after

Many cards offer a promotional or introductory APR — often 0% — for a set period on purchases, balance transfers, or both. This period typically lasts three to 21 months, depending on the card and the offer. During the promotional period, no interest accrues on that type of transaction, even if you carry a balance.

When the promotional period ends, your APR reverts to the standard rate for that transaction type. This happens automatically; you do not need to do anything. If you still carry a balance when the promotion expires, interest begins accruing at the full APR on the remaining balance. Your card issuer will notify you in writing before the promotion ends, but the responsibility to pay down the balance before the deadline falls on you.

A common strategy is to use a 0% balance transfer offer to move high-interest debt from one card to another, then pay aggressively during the promotional window. If you transfer $5,000 at 0% for 12 months, you have 12 months to pay it down without interest accruing. But if you still owe $2,000 when month 13 arrives, that $2,000 suddenly begins accruing interest at the card's standard balance transfer APR, which is often higher than the purchase APR.

How to find your card's APR

Your current APR appears on every monthly statement, usually near the top or in a section labeled "Interest Rates" or "APRs." If you have multiple APRs on the card (purchase, cash advance, balance transfer), each one is listed separately. The statement also shows the APR that applies to any promotional offers currently active on your account.

You can also log into your online account or call the customer service number on the back of your card to ask for your APR. The issuer must provide it immediately. If you are shopping for a new card, the APR is disclosed in the card's terms and conditions, usually in a document called the "Schumer Box" or "Summary of Terms," which credit card companies are required to provide before you open the account.

Your APR can change over time. If you have a variable APR, it changes automatically when the benchmark rate changes. If you have a fixed APR, the issuer can raise it if you miss a payment or if a promotional period ends, but they must notify you in writing at least 45 days in advance. You have the right to reject a rate increase and close the account, though you will still owe the existing balance at the old rate.

APR versus other costs on your card

APR is the interest rate, but it is not the only cost of carrying a balance. Your card may also charge an annual fee (paid once per year just to hold the card), late fees (if you miss a payment), over-limit fees (if you exceed your credit limit), and cash advance fees (a percentage of the amount withdrawn). These fees are separate from APR and are charged regardless of whether you carry a balance.

The total cost of using your card includes the APR plus any applicable fees. A card with a 15% APR and a $95 annual fee costs more than a card with an 18% APR and no annual fee if you do not carry a balance (because you pay no interest but still pay the annual fee). But if you carry a $5,000 balance for a year, the 15% APR card costs less overall despite the annual fee.

When comparing cards, look at the full picture: the APR, any annual fee, the grace period (how many days you have to pay before interest starts), and any promotional rates. A card with a higher APR but a longer grace period and no annual fee may cost you less than a card with a lower APR but a high annual fee and a short grace period.

Frequently Asked Questions

Does APR apply if I pay my full balance every month?

No. If you pay your entire statement balance by the due date, you pay no interest, and the APR does not affect you. Interest only accrues on balances you carry into the next billing cycle. This is why paying in full each month is the most cost-effective way to use a credit card.

Can my APR change after I open the account?

Yes. If your APR is variable, it changes automatically when the benchmark rate changes. If your APR is fixed, the issuer can raise it if you miss a payment or if a promotional period ends, but they must notify you in writing at least 45 days in advance. You can reject the increase and close the account, though you still owe the existing balance.

What is the difference between APR and interest?

APR is the annual rate expressed as a percentage. Interest is the actual dollar amount you owe based on that rate and your balance. If your APR is 20% and you carry a $1,000 balance for one month, your interest charge is roughly $16.67 (one-twelfth of 20% applied to $1,000).

If I transfer a balance at 0% APR, what happens when the promotion ends?

When the promotional period ends, any remaining balance on that transfer begins accruing interest at the card's standard balance transfer APR, which is usually 18% to 25%. The issuer notifies you in writing before the promotion expires, but you are responsible for paying down the balance before the deadline to avoid interest charges.

How does APR affect how long it takes to pay off a balance?

A higher APR means more of each payment goes toward interest and less toward reducing the principal, so it takes longer to pay off the balance. A $3,000 balance at 10% APR with $100 monthly payments takes about 31 months to clear, while the same balance at 25% APR takes about 39 months with the same payment amount.