A credit card is a loan you use for small purchases, paid back monthly with interest if you carry a balance

When you swipe or tap a credit card, you are borrowing money from the card issuer — usually a bank. You are not spending your own money. The issuer pays the merchant, and you owe the issuer that amount back. If you pay the full balance by the due date each month, you pay nothing extra. If you pay only part of it, the issuer charges you interest on what remains, and that interest compounds daily until you pay it off.

The card issuer makes money three ways: interest from people who carry balances, fees charged to merchants (which you never see), and annual fees on some cards. You control whether you pay interest by choosing to pay in full each month or to carry a balance. That choice is the single biggest factor in whether a credit card costs you money or saves you money.

Key Takeaways

  • A credit card is a short-term loan that you repay monthly; if you pay the full balance by the due date, you pay no interest.
  • Interest rates on credit cards are typically 15% to 25% per year, and interest accrues daily on any unpaid balance.
  • Your credit card activity is reported to credit bureaus and affects your credit score, which lenders use to decide whether to lend to you and at what rate.
  • Annual percentage rate (APR), grace period, credit limit, and minimum payment are the four terms that determine what a card actually costs you.
  • Rewards cards offer cash back or points but only save you money if you pay the full balance each month; otherwise, interest charges exceed any rewards.

The four numbers that determine what a credit card costs

Annual Percentage Rate (APR) is the yearly interest rate the card issuer charges on any balance you carry. Credit card APRs typically range from 15% to 25%, though some cards offer lower rates to people with very good credit, and some charge higher rates to people with poor credit. The APR is not fixed for the life of the card — the issuer can raise it if you miss a payment or if the prime rate (set by the Federal Reserve) rises. Your card agreement will say whether your APR is fixed or variable.

Grace period is the number of days between the end of your billing cycle and the due date. During this time, if you pay your full balance, no interest accrues. Most cards offer a grace period of 21 to 25 days. If you carry a balance from one month to the next, the grace period does not explore to new purchases — interest starts accruing when ready on anything new you charge. This is why paying in full each month is the cheapest way to use a credit card.

Credit limit is the maximum amount you can borrow on the card at any one time. The issuer sets this based on your credit score, income, and payment history. You can request a higher limit, but the issuer may or may not grant it. Staying well below your limit (financial advisors often suggest using no more than 30% of your available credit) helps your credit score.

Minimum payment is the smallest amount you must pay by the due date to avoid a late fee and credit damage. Minimum payments are typically 1% to 3% of your balance. Paying only the minimum means the rest of your balance carries forward to the next month and accrues interest. If you pay only the minimum on a large balance, it can take years to pay off and cost far more in interest than the original purchase.

How interest actually works on a credit card

Credit card interest is calculated daily, not monthly. Here is how it works: the issuer takes your average daily balance during the billing cycle, multiplies it by your APR, and divides by 365. That is the interest charged for that cycle. If your APR is 20% and your average daily balance is $1,000, you owe roughly $5.48 in interest for that month.

The problem is that interest compounds. If you pay $100 of that $1,000 balance, the remaining $900 accrues interest the next month, and the month after that, and so on. The longer you carry a balance, the more of your payment goes toward interest and the less toward the actual purchase. This is why carrying a balance on a credit card is one of the most expensive ways to borrow money.

Some cards offer a promotional 0% APR period for a set number of months — often 6 to 21 months for new cardholders or for balance transfers. During this period, no interest accrues on the balance, even if you pay only the minimum. Once the promotional period ends, the regular APR kicks in. If you still owe money at that point, interest charges jump significantly.

Credit cards and your credit score

Every time you use a credit card and every time you make a payment, that information is reported to the three major credit bureaus: Equifax, Experian, and TransUnion. Your credit score is built from this history. The factors that matter most are payment history (35% of your score), amounts owed relative to your credit limits (30%), length of credit history (15%), mix of credit types (10%), and recent credit inquiries (10%).

Missing a payment or paying late damages your score when ready and stays on your record for seven years. Carrying a high balance relative to your credit limit also hurts your score, even if you pay on time. Paying your full balance each month and never missing a due date builds your score over time. A higher credit score means you will may have access to for better interest rates on mortgages, car loans, and other forms of borrowing.

Closing a credit card can actually lower your score, even if you paid it off, because it reduces your total available credit and shortens your credit history. If you want to stop using a card, it is usually better to keep it open and unused than to close it.

Rewards cards: when they save you money and when they do not

Rewards cards offer cash back (usually 1% to 5% of purchases), points that convert to travel or merchandise, or other perks. The card issuer can afford to offer these rewards because merchants pay them a higher fee. If you pay your full balance each month, rewards are genuine savings — you get 1% to 2% back on everything you spend. If you carry a balance, the interest you pay far exceeds any rewards. A card offering 2% cash back is not a good deal if you are paying 20% interest on a carried balance.

Some rewards cards charge an annual fee ($95 to $450 or more) to offset the cost of rewards. These cards only make sense if your annual rewards exceed the fee. A card charging $95 per year and offering 2% cash back needs you to spend at least $4,750 per year just to break even. If you spend less than that, a no-fee card is cheaper, even if it offers lower rewards.

Fees beyond interest

Credit cards charge fees for specific actions. A late fee (typically $25 to $40) is charged if you miss the due date. A returned payment fee is charged if a check or automatic payment bounces. A cash advance fee (usually 3% to 5% of the amount) is charged if you withdraw cash using the card, and cash advances typically have a higher APR than regular purchases. A foreign transaction fee (usually 1% to 3%) is charged for purchases made outside the United States.

Some cards charge an annual fee just for holding the card, regardless of whether you use it. Others charge no annual fee. There is no reason to pay an annual fee unless the rewards or other benefits clearly exceed it. Over-limit fees (charged when you exceed your credit limit) have been largely eliminated by federal regulation, but some issuers still offer them as an option.

Frequently Asked Questions

What happens if I only pay the minimum payment?

You avoid a late fee and credit damage, but the remaining balance carries forward and accrues interest at your APR. If you owe $5,000 at 20% APR and pay only the minimum (typically 1% to 3% of the balance), it can take 10 to 15 years to pay off and cost $5,000 to $8,000 in interest alone. Paying more than the minimum is always cheaper in the long run.

Can I negotiate my APR if I have good credit?

Yes. Call your card issuer and ask for a lower rate, especially if you have made on-time payments and your credit score has improved since you opened the account. Issuers sometimes lower rates to keep customers from switching to competitors. The worst they can say is no. Even a 2% reduction saves significant money on a carried balance.

Does using a credit card hurt my credit score?

Using a credit card does not hurt your score if you pay on time and keep your balance low relative to your limit. In fact, responsible credit card use builds your score over time. What hurts your score is missing payments, carrying a very high balance, or opening many new cards in a short period.

What is the difference between a credit card and a debit card?

A debit card draws money directly from your bank account — you spend only what you have. A credit card is a loan you repay later. Debit cards offer no fraud protection in most cases and do not build credit history. Credit cards offer fraud protection by law and build credit if used responsibly, but they cost money if you carry a balance.

Should I close a credit card I am not using?

Usually no. Closing a card lowers your credit score by reducing available credit and shortening your credit history. If you want to stop using a card, keep it open with a zero balance. Use it occasionally for a small purchase to keep the account active. Only close a card if it charges an annual fee you do not want to pay.