What does APR mean on a credit card?

APR stands for Annual Percentage Rate — it's the yearly cost of borrowing including interest and some fees. A 24% APR means borrowing £100 for a year would cost roughly £24 in interest. However, credit card interest is calculated daily and charged monthly, so the actual maths is more complex.

Do I pay interest if I pay my credit card in full?

No. If you pay your full statement balance by the due date each month, you won't pay any interest on purchases. This is called the interest-free period or grace period. You only pay interest if you carry a balance from month to month.

Why is credit card interest so high?

Credit cards typically charge 20-30% APR because they are unsecured debt (no collateral) and high-risk for lenders. Unlike mortgages where the house is security, credit card debt can simply be unpaid. The high rates cover defaults, fraud, and the free credit offered to those who pay in full.

Credit Card Interest and APR Explained UK

Credit card interest can be expensive if you don’t understand how it works. Knowing when interest applies — and how to avoid it — can save you hundreds or thousands of pounds.

How Credit Card Interest Works

Scenario	Do You Pay Interest?
Pay full balance by due date	No
Pay less than full balance	Yes — on the remaining amount
Cash withdrawal	Yes — from day 1
Balance transfer	Depends on promotional rate
Carry any balance from last month	Often yes — even on new purchases

Understanding APR

What APR Includes

Component	Included in APR?
Interest rate	Yes
Annual fee	Yes (if applicable)
Cash advance fees	No (charged separately)
Late payment fees	No
Foreign transaction fees	No

Types of APR

APR Type	What It Applies To	Typical Range
Purchase APR	Normal card spending	18%–30%
Cash APR	ATM withdrawals, cash-like transactions	25%–35%
Balance transfer APR	Transferred debt	0% promo or 18%–30%
Default APR	After missed payments	Can be higher

Representative APR

What It Means	Reality
“24.9% APR Representative”	Only 51% must be offered this rate
Your rate could differ	Depending on your credit score
Some get higher rates	Up to 10-15 percentage points more
Some get declined	Don’t get the card at all

How Interest Is Calculated

The Maths

Step	Calculation
1. Daily interest rate	APR ÷ 365 = daily rate
2. Example: 24% APR	24% ÷ 365 = 0.0658% per day
3. Interest per day	Balance × daily rate
4. Monthly interest	Sum of daily interest charges

Simplified Example

Day	Balance	Daily Rate	Interest
1-30	£1,000	0.0658%	£0.66/day
30 days total	£1,000	—	~£19.70 for the month

Note: Actual calculations are more complex, accounting for payments and purchases throughout the month.

The Interest-Free Period

How It Works

Stage	What Happens
You make a purchase	No interest yet
Statement generated	Shows what you owe
Due date (21-25 days later)	Deadline for payment
Pay in full	No interest charged — free borrowing
Don’t pay in full	Interest charged on remaining balance

Length of Interest-Free Period

Purchase Date	Statement	Due Date	Interest-Free Days
Day after statement	Next statement (30 days)	25 days later	Up to 56 days
Day before statement	That statement	25 days later	~25 days

Maximum interest-free period: Typically 45-56 days (if you buy right after your statement date)

When You Lose It

Scenario	Interest-Free Period
Pay full balance every month	Maintained
Carry any balance	Often lost on new purchases too
Cash withdrawal	No interest-free period ever

Important: Once you carry a balance, new purchases may accrue interest from day 1 until you clear the balance completely.

Cash Withdrawals and Interest

Feature	Cash Withdrawal
Interest starts	Immediately (no grace period)
Rate	Usually higher than purchase APR
Fee	Typically 3-5% of amount (minimum £3-5)
When to use	Never unless emergency

Example: Cash Withdrawal Cost

Amount	Fee (3%)	Interest (30 days at 27% APR)	Total Cost
£100	£3	~£2.20	£5.20 for 30 days
£500	£15	~£11	£26 for 30 days

Minimum Payments and Interest

If you only pay the minimum:

Balance	APR	Monthly Payment	Time to Clear	Total Interest
£1,000	22%	Minimum (~£25)	5 years	~£500
£3,000	22%	Minimum (~£60)	14 years	~£2,600
£5,000	22%	Minimum (~£100)	18 years	~£5,000

The trap: Minimum payments are designed to keep you in debt for as long as possible.

Strategies to Minimise Interest

If You Pay in Full

Strategy	Benefit
Always pay full balance	Never pay interest on purchases
Set up Direct Debit for full balance	Can’t accidentally miss
Don’t carry a balance	Maintain interest-free period

If You Carry a Balance

Strategy	Benefit
Pay as much as possible	Faster payoff, less interest
Transfer to 0% balance transfer card	0% interest while you pay off
Stop using the card	Don’t add to the problem
Prioritise high-interest debt	Pay this before lower-rate loans

General Strategies

Strategy	Benefit
Never withdraw cash	Avoid expensive cash APR
Avoid cash-like transactions	Gambling, money orders, crypto
Check your rate	Know what you’re actually being charged
Look for 0% deals	If you need to spread costs

Special Situations

0% Promotional Rates

Feature	Detail
How they work	0% interest for a set period (typically 6-24 months)
After promo ends	Reverts to standard APR (often 20-30%)
Key risk	If not cleared in time, interest begins
Strategy	Set up payments to clear before 0% ends

Compound Interest

Most credit cards charge simple interest on the average daily balance, not compound interest. However, if you don’t pay, the balance increases and interest is then charged on the higher amount — which feels like compounding.

Interest on Interest-Free Purchases

Common Misconception	Reality
“This purchase is 0%, so my card has 0%”	The 0% only applies to specific transactions
“I can pay for other purchases later”	Other purchases may not be 0%
Which gets paid first?	Usually highest-interest debt, but check terms

Key Takeaways

Pay in full to never pay interest on purchases
Never use for cash — expensive from day 1
Don’t just pay minimums — debt trap
Carrying a balance? Consider 0% balance transfer
Know your APR — check your actual rate, not advertised
Set up Direct Debit for at least full balance

For help with existing debt, see our paying off credit card debt guide and balance transfer guide.