How credit card interest works, and what minimum payments really cost

A credit card costs nothing extra if you pay the full statement balance every month. Carry a balance, and interest starts building every day, on top of interest already charged. Knowing exactly how that works makes it easier to see why the minimum payment is the most expensive way to pay off a card.

APR is yearly; interest is charged daily

Your card's annual percentage rate (APR) is the yearly cost of borrowing. Many cards have more than one: a rate for purchases, another for cash advances, and sometimes others for things like convenience checks. Your statement has to list each rate and the balance it applies to.

Card APRs are high. In the Federal Reserve's G.19 consumer credit release of October 7, 2026, the average rate on credit card accounts that were charged interest was 22.36% in August 2026 (preliminary), and 21.19% across all accounts.

Card issuers do not charge that rate once a year. Many work out interest daily using a daily periodic rate, which is the APR divided by 365 or 360, depending on the issuer. At a 22% APR and a 365-day year, the daily rate is 0.0603%. Each day, that rate is applied to what you owe, and the interest is added to the balance, so tomorrow's interest is charged on today's interest too. This is daily compounding.

Average daily balance

Many issuers base the charge on your average daily balance: add up the balance at the end of each day in the billing cycle, then divide by the number of days.

A simple illustration, assuming you are already carrying a balance (so there is no grace period, see below): you start the cycle owing $1,000 for 20 days, then make a $500 purchase that sits on the card for the last 10 days. Your average daily balance is $1,166.67, and at a 22% APR the interest for the cycle comes to about $21.10. The later in the cycle a purchase lands, the less it adds; the earlier you pay, the more you save.

The grace period: how to pay zero interest

Most cards give a grace period on purchases: if you pay the full statement balance by the due date, new purchases are not charged interest. In the US, issuers must get your bill to you at least 21 days before the payment is due.

The grace period usually covers purchases only. Cash advances typically start accruing interest on the day you take them. And if you do not pay in full, you can lose the grace period: you pay interest on the unpaid amount, and new purchases start accruing interest from the day you make them. You may lose it for the month you did not pay in full and the following month too.

Minimum payments

The minimum payment is the smallest amount you can pay without being late. Each issuer sets its own formula; one style, used in the example below, is a percentage of the balance plus that month's interest, with a dollar floor. Because a large share of each minimum payment is interest, the balance falls slowly.

Your statement shows how long payoff would take at the minimum, and the monthly amount that would clear the current balance in 36 months, assuming no new charges. You only have to pay the minimum, but every dollar above it goes toward the balance and cuts future interest.

Worked example: $3,000 at 22%, minimum vs fixed payment

Assumptions for illustration only: a $3,000 balance, an illustrative 22% APR (close to the Fed's latest average for accounts paying interest), no new purchases and no fees. Interest compounds daily at 22% ÷ 365 over a 30-day billing cycle. The minimum payment is 1% of the balance plus that month's interest, or $25 if that is higher (or the full balance if smaller). The fixed plan pays $150 every month. Computed month by month.

The first month's interest is $54.72, so of the $85.27 minimum, only $30.55 reduces the debt itself. As the balance shrinks, the minimum shrinks with it, which is exactly why the minimum-only plan takes so long: the payment keeps falling, and the debt is still there 14 years 9 months later.

Paying a fixed $150 clears the same card 151 months sooner and saves $3,573 in interest. Nothing changed except the habit of paying a set amount rather than whatever the statement asks for.

To run your own numbers, use the debt payoff calculator. If you have several balances, our avalanche vs snowball guide shows which to pay first.

Ways to pay less interest

• Pay the statement balance in full whenever you can, so the grace period keeps purchases interest-free.
• Pay a fixed amount above the minimum, set as an automatic payment, so it does not shrink as the balance falls.
• Pay earlier in the cycle. With daily interest, a payment made mid-cycle lowers the average daily balance for the rest of the month.
• Stop adding new charges to a card you are paying down; use a debit card for a while.
• Watch your utilization. High balances relative to limits can weigh on your score, as our credit score guide explains.

What to do this week

1. Find the purchase APR on your latest statement and the "minimum payment warning" box showing how long the minimum would take.
2. Pick a fixed monthly payment you can sustain, ideally at least the 36-month figure on the statement, and set it as autopay.
3. Move new spending to a debit card until the balance is gone, then pay in full each month to keep the grace period.

General education, not personal financial advice. Figures are illustrations computed from the stated assumptions.