APR is the yearly interest rate, shown as a percentage, that a card issuer charges when you carry a balance

Your card's Annual Percentage Rate (APR) is the cost of borrowing money from your card issuer, expressed as a yearly percentage. 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 approximately $200 in interest charges on top of the original $1,000.

APR is not the same as a monthly interest rate, though card issuers calculate monthly charges using the APR. The issuer divides your APR by 12 to get a monthly rate, then applies that to your outstanding balance. This is why the same APR produces different dollar amounts depending on how much you owe and for how long.

Different cards carry different APRs. A card issuer sets your APR based on the creditworthiness you showed when you applied — typically ranging from around 15% to 29% for standard cards, though some specialty cards run higher or lower. The APR you receive may differ from the APR advertised, and it can change over time under certain conditions.

Key Takeaways

  • APR is a yearly percentage rate; the issuer converts it to a daily rate to calculate interest on your balance each day.
  • Interest charges accrue only on balances you carry past the due date — paying in full by the due date avoids interest entirely.
  • Most cards have multiple APRs: a standard purchase APR, a cash advance APR (usually higher), and a promotional APR (often 0% for a set period).
  • Your APR can increase if you miss a payment or violate your card agreement, and issuers must give you notice before most APR increases take effect.

When interest charges actually begin

Interest charges begin accruing the day after your statement closing date if you do not pay your full statement balance by the due date. Most cards offer a grace period — typically 21 to 25 days from the closing date to the due date — during which no interest accrues on new purchases, as long as you had no previous balance.

If you carry a balance from a previous month, the grace period does not apply to new purchases. Interest begins accruing on new purchases immediately, even if you pay them in full by the due date. This is why carrying a balance changes how the card works: you lose the interest-free window on everything you charge.

Cash advances do not receive a grace period at all. Interest on a cash advance begins accruing the moment you withdraw the cash, regardless of whether you pay it back before the due date. The APR for cash advances is also typically higher than the purchase APR — often 3 to 5 percentage points above your standard rate.

How the issuer calculates your interest charge

Card issuers use one of two methods to calculate interest: the average daily balance method or the adjusted balance method. The average daily balance method is far more common and typically results in higher interest charges.

Under the average daily balance method, the issuer adds up your balance at the end of each day in the billing cycle, divides by the number of days in the cycle, then multiplies by your daily periodic rate (your APR divided by 365). If you made a $500 purchase on day 5 of a 30-day cycle and made no other transactions, your average daily balance would be roughly $500 × 25 days ÷ 30 days, or about $417. The issuer then applies the daily rate to that average.

Under the adjusted balance method, the issuer simply takes your balance at the end of the billing cycle, subtracts any payments you made during that cycle, and applies the daily rate to that number. This method is less common because it produces lower interest charges for the issuer.

Your card agreement will state which method your issuer uses. You can find this information in the Schumer Box — the standardized disclosure table on your card's terms and conditions document — or by contacting the issuer directly.

Different APRs on the same card

A single card typically carries multiple APRs. Your purchase APR applies to regular transactions. Your cash advance APR applies to withdrawals from ATMs or cash-like transactions (balance transfers, money orders, gambling transactions). Your penalty APR applies if you miss a payment by 60 days or more, and is usually the highest rate on the card.

Many cards also offer a promotional APR, often 0% for a set period (typically 6 to 21 months) on purchases, balance transfers, or both. When the promotional period ends, the standard APR takes over. Promotional APRs are common on new card offers and balance transfer offers, but the terms vary widely — read the offer carefully to see what transactions may have access to and when the rate changes.

Your statement will break down charges by type, so you can see which APR applied to each transaction. If you carry balances across multiple APR categories, the issuer applies your payment to the lowest-APR balance first (by law), which means higher-APR balances accrue interest longer.

When your APR can increase

Your card issuer can raise your APR under specific circumstances. A penalty APR increase occurs when you miss a payment by 60 days or more; the issuer must notify you in writing before applying it. A penalty APR typically lasts at least six months, after which the issuer may lower it if you make on-time payments.

An introductory rate increase happens when a promotional APR expires and reverts to the standard APR. This is not a penalty — it is the scheduled end of the promotional offer. The issuer must disclose the reversion date in the original offer.

An APR increase due to market conditions is less common but possible. If your card agreement includes a variable APR clause, the issuer can adjust your rate based on changes to an index (usually the prime rate). The issuer must give you at least 45 days' notice before increasing a variable rate. You have the right to close the card rather than accept the increase, though you will still owe the balance at the old rate.

An issuer cannot increase your APR during the first year you hold the card, except for penalty APR increases or the expiration of a promotional rate. After the first year, increases are permitted under the terms of your agreement.

How to minimize interest charges

The simplest way to avoid interest is to pay your full statement balance by the due date each month. This keeps you within the grace period and costs you nothing in interest, regardless of your APR.

If you cannot pay the full balance, paying more than the minimum payment reduces the amount of interest you owe. Interest accrues on your remaining balance, so even a small extra payment lowers the total cost. For example, on a $5,000 balance at 20% APR, paying $200 per month instead of the minimum (often 1–3% of the balance) cuts your interest cost roughly in half and eliminates the debt years sooner.

A balance transfer to a card with a 0% promotional APR can pause interest charges for the promotional period, giving you time to pay down the balance without accruing additional interest. Balance transfers usually carry a fee (typically 3–5% of the amount transferred), so the math only works if the promotional period is long enough to offset the fee.

Requesting an APR reduction from your issuer is also an option, particularly if you have a good payment history or a higher credit score than when you opened the card. Issuers are not required to lower your rate, but some will negotiate, especially if you threaten to move your balance elsewhere.

How APR differs from other card costs

APR is the interest you pay on a balance you carry. It is separate from annual fees (charged once per year just for holding the card), late fees (charged when you miss a payment), foreign transaction fees (charged for purchases outside the US), and cash advance fees (a percentage of the amount withdrawn). A card can have a 0% APR but still charge an annual fee, or vice versa.

APR also differs from the effective APR you actually pay, which accounts for fees and the timing of your payments. A card with a 20% APR and a $95 annual fee costs more than a card with a 20% APR and no annual fee, even though the APR is identical. When comparing cards, look at the full cost picture, not just the APR.

Frequently Asked Questions

Does APR apply if I pay my full balance on time?

No. If you pay your full statement balance by the due date, no interest charges accrue, and your APR does not apply. The grace period protects you as long as you had no previous balance and you pay in full. This is why paying the full balance each month is the most cost-effective way to use a credit card.

What is the difference between APR and interest rate?

APR and interest rate are often used interchangeably, but APR technically includes fees in addition to the pure interest rate. For credit cards, the APR is the rate shown on your agreement and is what the issuer uses to calculate your interest charges. The terms are essentially the same for card purposes.

Can my APR change without notice?

Your APR can change when a promotional period ends (the issuer disclosed this in the original offer), or if you miss a payment by 60 days or more (the issuer must notify you first). Variable-rate APRs can change with market conditions, but the issuer must give you 45 days' notice. You cannot be surprised by a rate change without prior written notice.

If I make a partial payment, which balance gets paid first?

By law, your payment is applied first to the balance with the highest APR, then to lower-APR balances. This protects you by reducing the amount of interest you owe. If you carry a cash advance balance (higher APR) and a purchase balance (lower APR), your payment reduces the cash advance first.

How long does interest accrue if I only pay the minimum?

Interest accrues every month you carry a balance, for as long as the balance exists. If you pay only the minimum, most of your payment goes toward interest rather than principal, so the balance shrinks slowly. On a $5,000 balance at 20% APR, paying only the minimum can take 20+ years to eliminate the debt, with interest charges exceeding the original balance.