Credit Card Interest Calculator

See exactly how much interest a balance will cost you in one billing cycle — then learn, in plain English, how credit card interest actually works.

Your numbers

$
%
Interest this cycle
$18.83
You'd owe $1,018.83 total
$0.63
per day
0.063%
daily rate
$230
≈ a year of this
Pay in full and this is $0. Interest only kicks in when you carry a balance past the due date. More below.

Credit card interest, in plain English

The whole thing in five short ideas.

The #1 rule

1The grace period: pay in full, pay $0

If you pay your full statement balance by the due date every month, you never pay a cent of interest on purchases — no matter how high your APR is. The rate only matters if you carry a balance from one month to the next. So the whole game is: pay it off in full whenever you can.

How it's charged

2Interest is charged daily, not yearly

Even though the rate is quoted per year, the card charges you a little bit every single day you carry a balance. Each day it takes your balance and multiplies it by a tiny daily rate, then adds that to what you owe.

The math

3APR ÷ 365 = your daily rate

Your APR is the yearly rate. To get the daily rate, divide it by 365.

22.99% APR ÷ 365 ≈ 0.063% per day. On a $1,000 balance that's about 63¢ a day — roughly $19 over a 30-day cycle.
Which balance?

4They use your average daily balance

Not your end-of-month number. The issuer looks at your balance on every day of the cycle, adds them up, and divides by the number of days.

Start at $100, then a $45 charge posts on day 11: ten days at $100 plus twenty days at $145 averages to $130 — and that's what interest is charged on.
The trap

5The minimum payment is mostly interest

Your minimum is built to cover the interest plus a tiny slice of principal. Pay only the minimum and a balance can take years to clear and cost more in interest than the original purchase. Always pay more than the minimum when you can.

MyCreditPerks · This calculator is for estimates and education. Your card's exact interest depends on your issuer's method, your true average daily balance, and any fees. Not financial advice.