How Credit Cards Work: Interest, Fees and Rewards
Used well, a credit card is convenient, builds your credit and can earn rewards. Used badly, it gets expensive fast. Here's how interest and grace periods work, the fees to watch for, how to choose a card and how to use one without falling into debt.
By Pond.com editors Updated 4 min read
Quick answer
- Pay your statement balance in full every month and you won't pay interest on purchases, thanks to the grace period.
- Carry a balance and you'll pay interest at your card's APR. The average rate on cards charging interest was about 21.5% in early 2026.
- Paying only the minimum keeps you in debt for years and costs far more in interest.
- Watch for annual fees, late fees, cash advance fees and foreign transaction fees.
- Choose a card based on how you'll use it, such as building credit, earning rewards or paying down a balance.
A credit card lets you borrow money up to a set limit and pay it back later. Used well, it's one of the easiest ways to build credit, protect purchases and earn rewards. Used carelessly, it's one of the most expensive ways to borrow. The difference comes down to understanding how interest and fees work.
This guide is general information, not financial advice.
How a credit card works
- You make purchases up to your credit limit.
- At the end of each billing cycle (about a month), you get a statement showing your balance, minimum payment and due date.
- If you pay the full statement balance by the due date, you pay no interest on purchases.
- If you pay less, the rest carries over and the card charges interest on it.
Interest and APR
Your card's annual percentage rate (APR) is the yearly cost of borrowing. The average rate on credit card accounts that were charged interest was about 21.5% in early 2026, according to Federal Reserve data, and many cards charge more.
- Purchase APR applies to purchases you don't pay off in full.
- Cash advance APR is often higher, with no grace period, so interest starts right away.
- Penalty APR can apply after a late payment and can be close to 30%.
- Intro APR offers, such as 0% for 12 to 21 months, can help with big purchases or balance transfers if you pay the balance off before the offer ends.
Why minimum payments cost so much
The minimum payment is usually a small percentage of your balance. On a $5,000 balance at 22% APR, paying only the minimum could take well over a decade and cost thousands of dollars in interest. Your statement shows how long it would take, so check it.
The grace period
Most cards give you a grace period of at least 21 days between the statement date and the due date. Pay your full statement balance within that time and you'll pay no interest on purchases at all. Carry any balance, and you usually lose the grace period on new purchases until you pay in full again.
Fees to watch for
| Fee | What it is | How to avoid it |
|---|---|---|
| Annual fee | A yearly charge for some cards, often rewards cards | Choose a no-fee card unless the rewards clearly outweigh the fee |
| Late fee | Charged when you miss the minimum payment | Set up autopay |
| Cash advance fee | A fee, often 3 to 5%, for withdrawing cash | Use a debit card at your bank's ATM instead |
| Balance transfer fee | Usually 3 to 5% of the amount transferred | Make sure the interest savings outweigh the fee |
| Foreign transaction fee | Often about 3% on purchases abroad | Use a card with no foreign transaction fee when traveling |
Types of credit cards
| Type | Best for |
|---|---|
| Secured card | Building or rebuilding credit; you put down a refundable deposit |
| Student or starter card | First-time cardholders with little credit history |
| Cash back | Simple rewards on everyday spending |
| Travel rewards | Frequent travelers who pay in full; often have annual fees |
| Balance transfer | Paying down existing card debt at 0% for a set time |
| Low interest | People who sometimes carry a balance |
How to choose a card
- Know your goal: building credit, earning rewards or paying down debt.
- Check your credit first so you apply for cards you're likely to qualify for. Many issuers offer preapproval checks that don't affect your score.
- Compare the APR, fees and rewards, and read the terms for intro offers.
- Don't apply for several cards at once. Each application can cause a small, temporary dip in your score.
Using credit cards wisely
- Pay the full statement balance every month whenever you can.
- Keep your balance low compared with your limit. Using less than about 30% of your available credit, and ideally under 10%, helps your credit score.
- Never use a card for cash advances unless it's a true emergency.
- Check your statements for errors and fraud. Under federal law, your liability for unauthorized credit card charges is limited to $50, and most issuers offer zero liability.
Common questions
If you don't pay your full statement balance by the due date, the card charges interest on the remaining balance at its annual percentage rate (APR), usually calculated daily. Cash advances usually start charging interest right away, often at a higher rate.
The time between the end of a billing cycle and the payment due date, usually at least 21 days. If you pay your full statement balance by the due date, you pay no interest on purchases. If you carry a balance, you usually lose the grace period on new purchases until you pay in full again.
It can. Closing a card reduces your total available credit, which can raise your credit utilization ratio, and over time can shorten your average account age. If a card has no annual fee, keeping it open and using it occasionally is often better for your score.
A no-annual-fee starter card or a secured card, where you put down a deposit that becomes your credit limit. Use it for small purchases and pay it off in full each month to build a credit history.
Yes, if you pay in full every month and the rewards beat any annual fee. If you carry a balance, interest charges will usually wipe out any rewards you earn, so a low-rate card is a better choice.