The average credit card APR in the US hit 22.8% in early 2025, according to the Federal Reserve, the highest it’s been in decades. In the UK, the average sits around 23–25%, per Bank of England data.
Most people know credit cards charge interest. Fewer understand how it’s actually calculated, and that gap costs a lot of money. Carry a $3,000 / £2,400 balance at 23% APR and you’re paying roughly $57 / £46 a month just in interest. That’s money that doesn’t reduce your balance, doesn’t buy anything, and doesn’t stop until the balance is gone.
What APR actually means
APR stands for Annual Percentage Rate. It’s the yearly cost of borrowing, expressed as a percentage of the amount you owe.
Credit card interest isn’t charged annually, though. It’s charged daily. A 22% APR gets divided by 365 to produce a daily periodic rate of roughly 0.0603%. That rate applies to your balance every single day of the billing cycle.
On its own, 0.0603% sounds harmless. The problem is that it compounds: once interest accrues and you don’t pay it off, that interest starts generating interest of its own.
How the calculation actually works
Most credit card issuers use the average daily balance method. Your balance is recorded every day of the billing cycle (usually 28–31 days). Those daily figures are averaged together. That average is multiplied by the daily rate and the number of days in the cycle.
If you carry a $1,000 / £800 balance for a full 30-day cycle at 22% APR:
$1,000 × (22% ÷ 365) × 30 = $18.08 in interest
That’s one month. Keep carrying the balance on minimum payments and the following month’s interest is calculated on a slightly higher base, because last month’s interest gets added to what you owe. This is how a modest-seeming rate turns into thousands of pounds or dollars over time.
How to pay zero interest: the grace period
Most credit cards come with a grace period: the window between your statement closing date and your payment due date where no interest accrues on purchases. In the US this is legally required to be at least 21 days. In the UK it’s typically 25–56 days depending on the card.
Pay your full statement balance by the due date every month and you pay zero interest. The card becomes a short-term, interest-free loan that resets each billing cycle.
The grace period only applies when you carry no balance from the previous month. Pay in full last month and new purchases are interest-free until your next due date. Carry even a small balance over and you lose the grace period, with interest accruing on new purchases from the day you make them.
This trips a lot of people up. They carry $50 from one month, assume it’s basically nothing, and suddenly find themselves paying interest on a big purchase they thought they’d cleared.
The simplest fix is autopay set to the full statement balance, not the minimum. You’ll never accidentally carry a balance, and you’ll pay nothing in interest. But this only works if you have the cash to back it up, which is why having a budget that actually works matters before leaning on a credit card.
The minimum payment trap
Minimum payments are usually set at 1–2% of your outstanding balance in the US (with a floor of around $25–$35), or 1–3% in the UK (minimum typically £25). That seems manageable. The problem is that at a high APR, most of the minimum payment goes straight to interest. The balance barely moves.
A worked example
Take a $5,000 / £4,000 balance on a card charging 22% APR, with minimum payments of 2% of the balance (floor of $25 / £25):
Paying the minimum, it would take roughly 17–18 years to clear, with approximately $4,200 / £3,400 in interest on top. You’d pay back nearly double what you originally owed.
Switch to a fixed payment of $200 / £160 a month and you’d clear it in about 30 months, paying around $940 / £750 in interest.
The only change is an extra $165 / £135 a month. The payoff is 15 fewer years in debt and more than $3,000 / £2,600 saved. The numbers barely feel like the same scenario.
Card issuers set minimum payments low on purpose. Longer balances mean more interest paid. It’s not illegal. It’s just how the product is designed.
If you’re already in the minimum payment cycle, the debt payoff strategies in this article are worth reading. The key is committing to a fixed monthly amount that actually dents the balance rather than just keeping it stable.
How your APR is set
Your credit card APR is primarily driven by your credit score. The better your credit history, the lower the rate a lender will offer. In the US, someone with a 750+ FICO score might qualify for a card at 16–18% APR, while the same card might charge a 620-score holder 26–28%. In the UK the principle is the same: lenders use your credit file to price the risk.
The type of card plays a role too. Rewards and travel cards tend to carry higher APRs than basic cards, because the points and perks have to be funded somehow. If you always pay in full, that’s fine. If you ever carry a balance, a high-rewards card at 28% APR is a bad trade.
Most credit cards have variable rates tied to a benchmark: the US Prime Rate or the Bank of England base rate. When those go up, card APRs tend to follow within a billing cycle or two. That’s been a real factor since 2022. Your card’s terms will describe the rate as something like “Prime Rate + 14.99%”.
Promotional 0% APR offers are worth understanding on their own terms. Many cards advertise 0% interest for an introductory period (12–21 months in the US, 6–20 months in the UK) on purchases, balance transfers, or both. They can be genuinely useful, but only if you clear the balance before the promotional period ends. After it expires, the standard APR applies to whatever’s left, and that rate is often higher than average.
A few things that make it worse
Cash advances are in a different category to regular purchases. Withdrawing cash on a credit card typically comes with a higher APR (often 27–30% in the US, similar in the UK), no grace period, and a transaction fee of around 3–5%. Interest starts the moment you take the cash out, not at the end of the billing cycle. It should be a genuine last resort.
Deferred interest is not the same as a 0% promotional rate, and the difference matters. Common on retail store cards, deferred interest means that if you haven’t paid the entire balance by the end of the promotional period, all the held-back interest gets added to your balance at once, calculated from day one of the promotion. The fine print will say “deferred interest” rather than “0% APR”. Read carefully before signing up for anything at a checkout counter.
Balance transfers let you move existing debt to a new card at a lower or 0% rate. The transfer fee (usually 3–5% of the balance) adds to what you owe upfront, and you need a clear repayment plan before the promotional window closes. Without one, you’re just rescheduling the problem.
Don’t pay for money you already spent
By the time you’re paying credit card interest, you’ve already spent the money. The interest is the price of having spent it before you had it. Sometimes that’s unavoidable. For everyday spending, it’s a cost you can skip entirely by paying in full each month.
If you’re currently carrying no balance, an emergency fund is what keeps it that way. When something unexpected hits, the fund covers it and the card stays at zero.
Use the card. Just make sure you’re the one getting the benefit.