How Credit Card Interest Works

Credit card interest can feel like a mystery: you pay every month, but the balance barely moves. Once you see how it’s calculated, it’s easier to see where the money goes and how to keep more of it.

APR: the yearly price of borrowing

Your card’s APR (annual percentage rate) is the yearly interest rate on balances you carry. Many cards have more than one APR:

• Purchase APR for everyday purchases.
• Balance transfer APR, sometimes a low promotional rate for a set time.
• Cash advance APR, usually higher, with interest that often starts right away.
• Penalty APR, a higher rate that may apply after a late payment, as your card agreement explains.

Most cards have a variable APR, which can go up or down with a benchmark interest rate. Your card agreement and monthly statement list your rates.

The grace period: how to pay no interest

According to the CFPB, a grace period is the time between the end of a billing cycle and your payment due date. Card companies must send your bill at least 21 days before the payment is due.

If you pay your full statement balance by the due date, most cards charge no interest on purchases. If you don’t, the CFPB explains that you lose the grace period and are charged interest on the unpaid balance, and you may not get the grace period back right away. That means new purchases can start collecting interest too, until you pay in full again.

How interest is calculated

Most cards turn the APR into a daily rate and charge it on your balance each day. Here’s a simplified version:

1. Daily rate = APR ÷ 365. A 24% APR is about 0.066% a day.
2. Each day, the daily rate is applied to that day’s balance.
3. At the end of the billing cycle, the daily charges are added up and appear as interest on your statement.

Because interest is based on your daily balance, paying earlier in the cycle, or making more than one payment a month, can lower the interest you’re charged.

A quick example

These numbers are only for illustration. Say you carry a $3,000 balance on a card with a 24% APR:

	Amount
Daily rate	about 0.066%
Interest per day on $3,000	about $1.97
Interest for a 30-day month	about $59

If your minimum payment is $90, roughly two-thirds of it goes to interest that month, and only about $31 reduces what you owe. Your statement includes a minimum payment warning showing how long it would take to pay off the balance with minimum payments alone. Read why paying only the minimum keeps you in debt.

Fees that add to the cost

• Late fees if you miss the due date.
• Balance transfer fees, often a percentage of the amount moved.
• Cash advance fees plus the higher cash advance APR.
• Annual fees on some cards.

How to pay less interest

• Pay more than the minimum. Every extra dollar goes straight to the balance.
• Pay early, or twice a month. A lower daily balance means less interest.
• Target your highest-rate card first. That’s the debt avalanche. Our guide to the debt avalanche and debt snowball shows how.
• Ask for a lower APR. Calling your card company costs nothing.
• Avoid cash advances. They’re among the most expensive ways to borrow.
• Consider lower-rate options carefully, like a consolidation loan or balance transfer. See debt settlement vs. debt consolidation.

When interest is outpacing you

If most of your payment goes to interest and the balance won’t move, a nonprofit credit counselor may be able to arrange lower rates through a debt management plan. You can find one through the NFCC. If you’re falling behind, read what happens if you stop paying your credit cards before you decide what to do.

The bottom line

Interest is charged on the balance you carry, day by day. Pay in full when you can to keep your grace period. When you can’t, pay as much as you can, as early as you can, and focus extra money on your highest-rate card.

Sources: CFPB: what is a grace period for a credit card · NFCC